You might notice a lot of respondents listing their source of stress as related to work, finances, relationships, health or lack of time. Once you have drawn up your codebook, you are almost ready to enter your data. Before you can access these windows, you need to either open an existing data file or create one of your own.
So, in this chapter we will cover how to open and close SPSS; how to open and close existing data files; and how to create a data file from scratch.
We will then go on to look at the different windows SPSS uses. Place your cursor on the icon and double-click. This may vary depending on your computer and the SPSS licence that you have. The Open File dialogue box will allow you to search through the various directories on your computer to find where your data file is stored. You should always open data files from the hard drive of your computer. If you have data on a memory stick or flash drive, transfer it to a folder on the hard drive of your computer before opening it.
Find the file you wish to use and click on Open. Remember, all SPSS data files have a. The data file will open in front of you in what is labelled the Data Editor window more on this window later. This can be useful, but also potentially confusing.
You must keep at least one data file open at all times. If you close a data file, SPSS will ask if you would like to save the file before closing. Saving a data file When you first create a data file or make changes to an existing one e. This does not happen automatically.
So save yourself the heartache and save regularly. To save a file you are working on, go to the File menu top left-hand corner and choose Save. Or, if you prefer, you can also click on the icon that looks like a floppy disk, which appears on the toolbar at the top left of your screen. This will save your file to whichever drive you are currently working on. This should always be the hard drive—working from a flash drive is a recipe for disaster!
I have had many students come to me in tears after corrupting their data file by working from an external drive rather than from the hard disk.
When you first save a new data file, you will be asked to specify a name for the file and to indicate a directory and a folder in which it will be stored. Choose the directory and then type in a file name. SPSS will automatically give all data file names the extension.
This is so that it can recognise it as a data file. Opening a different data file If you finish working on a data file and wish to open another one, click on File, select Open, and then slide across to Data. Find the directory where your second file is 15 16 Getting Started stored.
Click on the desired file and then click the Open button. This will open the second data file, while still leaving the first data file open in a separate window.
It is a good idea to close files that you are not currently working on—it can get very confusing having multiple files open. Starting a new data file Starting a new data file is easy. Click on File, then, from the drop-down menu, click on New and then Data. From here you can start defining your variables and entering your data.
Before you can do this, however, you need to understand a little about the windows and dialogue boxes that SPSS uses. These are discussed in the next section. These windows are summarised here, but are discussed in more detail in later sections of this book.
When you begin to analyse your data, you will have a number of these windows open at the same time. Some students find this idea very confusing.
Once you get the hang of it, it is really quite simple. You will always have the Data Editor open because this contains the data file that you are analysing. Once you start to do some analyses, you will have the Viewer window open because this is where the results of all your analyses are displayed, listed in the order in which you performed them.
The different windows are like pieces of paper on your desk—you can shuffle them around, so that sometimes one is on top and at other times another. Each of the windows you have open will be listed along the bottom of your screen. To change windows, just click on whichever window you would like to have on top. You can also click on Window on the top menu bar.
This will list all the open windows and allow you to choose which you would like to display on the screen. Sometimes the windows that SPSS displays do not initially fill the screen.
It is much easier to have the Viewer window where your results are displayed enlarged on top, filling the entire screen. To do this, look on the top right-hand area of your screen. There should be three little buttons or icons. Click on the middle button to maximise that window i. If you wish to shrink it again, just click on this middle button. Data Editor window The Data Editor window displays the contents of your data file, and in this window you can open, save and close existing data files, create a new data file, enter data, make changes to the existing data file, and run statistical analyses see Figure 3.
If it does not open automatically, click on Window from the menu and this should be listed. This window displays the results of the analyses you have conducted, including tables and charts. In this window you can modify the output, delete it, copy it, save it, or even transfer it into a Word document. The Viewer screen consists of two parts. On the left is an outline or navigation pane, which gives you a full list of all the analyses you have conducted. You can use this side to quickly navigate your way around your output which can become very long.
Just click on the section you want to move to and it will appear on the righthand side of the screen. On the right-hand side of the Viewer window are the results of your analyses, which can include tables and graphs also referred to as charts in SPSS.
If you are using a version of SPSS prior to version 18, your output will be given a. To 18 Getting Started Figure 3. To save the results of your analyses, you must have the Viewer window open on the screen in front of you. Click on File from the menu at the top of the screen. Click on Save. Choose the directory and folder in which you wish to save your output, and then type in a file name that uniquely identifies your output.
To name my files, I use an abbreviation that indicates the data file I am working on and the date I conducted the analyses. For example, the file survey8may I keep a log book that contains a list of all my file names, along with details of the analyses that were performed. This makes it much easier for me to retrieve the results of specific analyses.
When you begin your own research, you will find that you can very quickly accumulate a lot of different files containing the results of many different analyses. To prevent confusion and frustration, get organised and keep good records of the analyses you have done and of where you have saved the results.
It is important to note that the output file with a. This can be a problem if you, or someone that needs to read the output, does not have SPSS available. You can choose the format that you would like to use e. Use the Browse button to identify the folder you wish to save the file into, specify a suitable name in the Save File pop-up box that appears and then click on Save and then OK. Select these in the Viewer window using the left-hand navigation pane. With the selections highlighted, select File from the menu and choose Export.
In the Export Output dialog box you will need to tick the box at the top labelled Selected and then select the format of the file and the location you wish to save to. Printing output You can use the navigation pane left-hand side of the Viewer window to select particular sections of your results to print out.
To do this, you need to highlight the sections that you want. Click on the first section you want, hold down the Ctrl key on your keyboard and then just click on any other sections you want.
To print these sections, click on the File menu from the top of your screen and choose Print. SPSS will ask whether you want to print your selected output or the whole output.
To modify a table you need to double-click on it, which takes you into what is known as the Pivot Table Editor. You can use this editor to change the look of your table, the size, the fonts used and the dimensions of the columns—you can even swap the presentation of variables around transpose rows and columns.
If you click the right mouse button on a table in the Viewer window, a pop-up menu of options that are specific to that table will appear. If you double-click on a table and then click on your right mouse button even more options appear, including the option to Create Graph using these results. You may need to highlight the part of the table that you want to graph by holding down the Ctrl key while you select the parts of the table you want to display.
Chart Editor window When you ask SPSS to produce a histogram, bar graph or scatterplot, it initially displays these in the Viewer window. If you wish to make changes to the type or presentation of the chart, you need to go into the Chart Editor window by double-clicking on your chart. In this window you can modify the appearance and format of your graph, change the fonts, colours, patterns and line markers see Figure 3. The procedure to generate charts and to use the Chart Editor is discussed further in Chapter 7.
Although the options available through the SPSS menus are usually all that most undergraduate students need to use, there are some situations when it is useful to go behind the scenes and to take more control over the analyses that you wish to conduct.
Syntax is a good way of keeping a record of what commands you have used, particularly when you need to do a lot of recoding of variables or computing new variables demonstrated in Chapter 8. It is also useful when you need to repeat a lot of analyses or generate a number of similar graphs. It allows you to copy and paste commands, and to make modifications to the commands generated by SPSS. Quite complex commands can also be written to allow more sophisticated recoding and manipulation of the data.
Warning: this is not for beginners— it is quite complex to follow. The commands pasted to the Syntax Editor are not executed until you choose to run them.
To run the command, highlight the specific command making sure you include the final full stop , or select it from the left-hand side of the screen, and then click on the Run menu option or the arrow icon from the menu bar.
Extra comments can be added to the syntax file by starting them with an asterisk see Figure 3. Syntax is stored in a separate text file with a. Make sure you have the syntax editor open in front of you and then select File from the menu. Select the Save option from the drop-down menu, choose the location you wish to save the file to and then type in a suitable file name. Click on the Save button. The syntax file with the extension. Sometimes it may be useful to copy and paste the syntax text from the Syntax Editor into a Word document so that you or others can view it even if SPSS is not available.
Choose Edit from the menu and then select Copy from the drop-down menu. Open a Word document and paste this material using the Edit, Paste option or hold the Ctrl key down and press V on the keyboard.
These choices are displayed in drop-down menus across the top of the screen, and also as icons. Try not to become overwhelmed; initially, just learn the key ones, and as you get a bit more confident you can experiment with others.
This is done in a dialogue box. Figure 3. To see this, click on Analyze from the menu at the top of the screen, and then select Descriptive Statistics and then slide across and select Frequencies. This will display a dialogue box asking you to nominate which variables you want to use see Figure 3. Selecting variables in a dialogue box To indicate which variables you want to use you need to highlight the selected variables in the list provided by clicking on them , then click on the arrow button in 22 Getting Started Figure 3.
You can select variables one at a time, clicking on the arrow each time, or you can select a group of variables. If the variables you want to select are all listed together, just click on the first one, hold down the Shift key on your keyboard and press the down arrow key until you have highlighted all the desired variables.
Click on the arrow button and all of the selected variables will move across into the Variable s box. If the variables you want to select are spread throughout the variable list, you should click on the first variable you want, hold down the Ctrl key, move the cursor down to the next variable you want and then click on it, and so on.
Once you have all the desired variables highlighted, click on the arrow button. They will move into the box. To remove a variable from the box, you just reverse the process. Click on the variable in the Variable s box that you wish to remove, click on the arrow button, and it shifts the variable back into the original list.
You will notice the direction of the arrow button changes, depending on whether you are moving variables into or out of the Variable s box. This is useful if you wish to keep a record of the command or repeat an analysis a number of times.
Reset: This button is used to clear the dialogue box of all the previous commands you might have given when you last used this particular statistical technique or procedure. It gives you a clean slate to perform a new analysis, with different variables. Cancel: Clicking on this button closes the dialogue box and cancels all of the commands you may have given in relation to that technique or procedure. Help: Click on this button to obtain information about the technique or procedure you are about to perform.
Although I have illustrated the use of dialogue boxes in Figure 3. Each will have a series of buttons with a variety of options relating to the specific procedure or analysis. These buttons will open subdialogue boxes that allow you to specify which analyses you wish to conduct or which statistics you would like displayed.
Click on Exit. SPSS will prompt you to save your data file and a file that contains your output. You should not rely on the fact that SPSS will prompt you to save when closing the program. It is important that you save both your output and your data file regularly throughout your session. If SPSS crashes or there is a power cut you will lose all your work. Click on Help from the menu bar and a number of choices are offered. You can ask for specific topics, work through a Tutorial, or consult a Statistics Coach.
This takes you step by step through the decision-making process involved in choosing the right statistic to use. This is not designed to replace your statistics books, but it may prove a useful guide. Within each of the major dialogue boxes there is an additional Help menu that will assist you with the procedure you have selected. These include creating the data file and entering the information obtained from your study in a format defined by your codebook covered in Chapter 2.
The data file then needs to be checked for errors, and these errors corrected. Part Two of this book covers these two steps. In Chapter 4, the procedures required to create a data file and enter the data are discussed. In Chapter 5, the process of screening and cleaning the data file is covered.
The flow chart shown on the next page outlines the main steps that are needed. In this chapter I will lead you through the process of creating a data file and entering the data. The first step is to check and modify, where necessary, the options that SPSS uses to display the data and the output that is produced. Step 2. Step 3. The final step is to enter the data—that is, the values obtained from each participant or respondent for each variable.
To illustrate these procedures I have used the data file survey4ED. The codebook used to generate these data is also provided in the Appendix. You can set up a basic data file on Excel and enter the data at home. When complete, you can then import the file into SPSS and proceed with the data manipulation and data analysis stages. The instructions for using Excel to enter the data are provided later in this chapter. The options allow you to define how your variables will be displayed, the type of tables that will be displayed in the output and many other aspects of the program.
Some of this will seem confusing at first, but once you have used the program to enter data and run some analyses you may want to refer back to this section.
Creating a data file and entering data 29 If you are sharing a computer with other people e. Sometimes other students will change these options, which can dramatically influence how the program appears. It is useful to know how to change things back to the way you want them. To open the Options screen, click on Edit from the menu at the top of the screen and then choose Options.
The screen shown in Figure 4. I have described the key ones below, organised by the tab they appear under. To move between the various tabs, just click on the one you want.
General tab When you come to do your analyses, you can ask for your variables to be listed in alphabetical order or by the order in which they appear in the file. I always use the Figure 4. To keep the variables in file order, just make sure the option File in the Variable Lists section is selected. In the Output section on the right-hand side, place a tick in the box No scientific notation for small numbers in tables.
This will stop you getting some very strange numbers in your output for the statistical analyses. In the Notification section, make sure the options Raise viewer window and Scroll to new output are selected.
This means that when you conduct an analysis the Viewer window will appear, and the new output will be displayed on the screen. Data tab Click on the Data tab to make changes to the way that your data file is displayed. If your variables do not involve values with decimal places, you may like to change the display format for all your variables.
This means that all new variables will not display any decimal places. This reduces the size of your data file and simplifies its appearance. Output Labels tab The options in this section allow you to customise how you want the variable names and value labels displayed in your output.
In the very bottom section under Variable values in labels are shown as: choose Values and Labels from the drop-down options. This will allow you to see both the numerical values and the explanatory labels in the tables that are generated in the Viewer window. Charts tab Click on the Charts tab if you wish to change the appearance of your charts. You can alter the Chart Aspect Ratio if you wish. You can also make other changes to the way in which the chart is displayed e.
Pivot Tables tab SPSS presents most of the results of the statistical analyses in tables called pivot tables. Under the Pivot Tables tab you can choose the format of these tables from an extensive list.
It is a matter of experimenting to find a style that best suits your needs. When I am first doing my analyses, I use a style called CompactBoxed. This saves space and paper when printing. However, this style is not suitable for importing into documents that are being sent for publication in a journal because it includes vertical lines.
You can change the table styles as often as you like—just remember that you have to change the style before you run the analysis. You cannot change the style of the Creating a data file and entering data 31 tables after they appear in your output, but you can modify many aspects e.
This can be activated by doubleclicking on the table that you wish to modify. Once you have made all the changes you wish to make on the various Options tabs, click on OK. You can then proceed to define your variables and enter your data.
You will do this in the Data Editor window see Figure 4. You can move between these two views using the little tabs at the bottom left-hand side of the screen. You will notice that in the Data View window each of the columns is labelled var. These will be replaced with the variable names that you listed in your codebook see Figure 4.
Down the side you will see the numbers 1, 2, 3 and so on. These are the case numbers that SPSS assigns to each of your lines of data. These are not the same as your ID numbers, and these case numbers change if you sort your file or split your file to analyse subsets of your data.
Procedure for defining your variables To define each of the variables that make up your data file, you first need to click on the Variable View tab at the bottom left of your screen. In this view see Figure 4. Your job now is to define each of your variables by specifying the required information for each variable listed in your codebook.
Some of the information you will need to provide yourself e. These default values can be changed if necessary. The key pieces of information that are needed are described below. The headings I have used correspond to the column headings displayed in the Variable View.
I have provided the simple stepby-step procedures below; however, there are a number of shortcuts that you can use once you are comfortable with the process. You should become familiar with the basic techniques first.
Name In this column, type in the brief variable name that will be used to identify each of the variables in the data file listed in your codebook. Keep these variable names as short as possible, not exceeding 64 characters. Each variable name must be unique, must start with a letter, and cannot contain spaces or symbols.
For ideas on how to label your variables, have a look at the codebooks provided in the Appendix. These list the variable names used in data files that accompany this book see p.
Type The default value for Type that will appear automatically as you enter your first variable name is Numeric. For most purposes, this is all you will need to use. There are some circumstances where other options may be appropriate.
For example, if you need to enter text information e. A Date option is also available if your data includes dates. To change the variable type, click in the cell and a box with three dots should appear giving you the options available. You can also use this window to adjust the width of the variable and the number of decimal places.
Width The default value for Width is 8. This is usually sufficient for most data. If your variable has very large values or you have requested a string variable , you may need to change this default value; otherwise, leave it as is. Creating a data file and entering data Decimals The default value for Decimals is usually 2 however, this can be changed using the Options facility described earlier in this chapter.
If your variable has decimal places, change this to suit your needs. Label The Label column allows you to provide a longer description for your variable than used in the Name column. This will be used in the output generated from the analyses conducted by SPSS. Values In the Values column you can define the meaning of the values you have used to code your variables.
I will demonstrate this process for the variable Sex. Click on the three dots on the right-hand side of the cell. This opens the Value Label dialogue box. Click in the box marked Value. Type in 1. Click in the box marked Label. Type in Male. Click on Add. Repeat for Females: Value: enter 2, Label: enter Female.
When you have finished defining all the possible values as listed in your codebook , click on OK. Missing Sometimes researchers assign specific values to indicate missing values for their data. This is not essential—SPSS will recognise any blank cell as missing data. So if you intend to leave a blank when a piece of information is not available, it is not necessary to do anything with this Variable View column.
If you do intend to use specific missing value codes e. Click in the cell and then on the shaded box with three dots that appears. Choose the option Discrete missing values and type the value e. Up to three values can be specified. Click on OK. If you are using these special codes, it is also a good idea to go back and label these values in the Values column. Columns The default column width is usually set at 8, which is sufficient for most purposes. Change it only if necessary to accommodate your values or long variable names.
There is no need to change this. Measure The column heading Measure refers to the level of measurement of each of your variables. The default is Scale, which refers to continuous data measured at interval or ratio level of measurement.
If your variable consists of categories e. Choose Nominal for categorical data and Ordinal if your data involve rankings or ordered values e. Optional shortcuts The process described above can be rather tedious if you have a large number of variables in your data file. There are a number of shortcuts you can use to speed up the process. Copying variable definition attributes to one other variable 1.
In Variable View, click on the cell that has the attribute you wish to copy e. From the menu, click on Edit and then Copy. Click on the same attribute cell for the variable you wish to apply this to.
From the menu, click on Edit and then Paste. Copying variable definition attributes to a number of other variables 1.
Click on the same attribute cell for the first variable you wish to copy to and then, holding your left mouse button down, drag the cursor down the column to highlight all the variables you wish to copy to. Setting up a series of new variables all with the same attributes If your data consists of scales made up of a number of individual items, you can create the new variables and define the attributes of all of these items in one go.
The Creating a data file and entering data procedure is detailed below, using the six items of the Optimism Scale as an example optim1 to optim6. If you want to practise this as an exercise, you should start a new data file File, New, Data. In Variable View, define the attributes of the first variable optim1 following the instructions provided earlier. With the Variable View selected, click on the row number of this variable this should highlight the whole row.
From the menu, select Edit and then Copy. Click on the row number of the next empty row. From the menu, select Edit and then Paste Variables. In the dialogue box that appears, enter the number of additional variables you want to add in this case, 5. Enter the prefix you wish to use optim and the number you wish the new variables to start on in this case, 2.
This will give you five new variables optim2, optim3, optim4, optim5 and optim6. To set up all of the items in other scales, just repeat the process detailed above e. Remember, this procedure is suitable only for items that have all the same attributes; it is not appropriate if the items have different response scales e.
Make sure you have your codebook ready. Procedure for entering data 1. To enter data, you need to have the Data View active. Click on the Data View tab at the bottom left-hand side of the screen of the Data Editor window. A spreadsheet should appear with your newly defined variable names listed across the top. Click on the first cell of the data set first column, first row.
Type in the number if this variable is ID, this should be 1. Press the right arrow key on your keyboard; this will move the cursor into the second cell, ready to enter your second piece of information for case number 1.
Move across the row, entering all the information for case 1, making sure that the values are entered in the correct columns. To move back to the start, press the Home key on your keyboard on some computers you may need to hold the Ctrl key or the Fn key down and then press the Home key. Press the down arrow to move to the second row, and enter the data for case 2. If you make a mistake and wish to change a value, click in the cell that contains the error. Type in the correct value and then press the right arrow key.
After you have defined your variables and entered your data, your Data Editor window should look something like that shown previously in Figure 3. If you have entered value labels for some of your variables e.
To do this, click on View from the menu and select the option Value Labels. This option can also be activated during the data entry process so that you can choose an option from a drop-down menu, rather than typing a number in each cell. This is slower, but does ensure that only valid numbers are entered. To turn this option off, go to View and click on Value Labels again to remove the tick. Make sure you have the Data Editor window open on the screen, showing Data View. Delete a case Move down to the case row you wish to delete.
Position your cursor in the shaded section on the left-hand side that displays the case number. Click once to highlight the row. Press the Delete button on your computer keyboard. You can also click on the Edit menu and click on Clear. Insert a case between existing cases Move your cursor to a cell in the case row immediately below where you would like the new case to appear. Click on the Edit menu and choose Insert Cases. An empty row will appear in which you can enter the data of the new case.
Delete a variable Position your cursor in the shaded section which contains the variable name above the column you wish to delete. Click once to highlight the whole column. Press the Delete button on your keyboard. Creating a data file and entering data Insert a variable between existing variables Position your cursor in a cell in the column variable to the right of where you would like the new variable to appear.
Click on the Edit menu and choose Insert Variable. An empty column will appear in which you can enter the data of the new variable. Highlight the variable you wish to move by clicking in the left-hand margin.
Click and hold your left mouse button and then drag the variable to the new position a red line will appear as you drag. Release the left mouse button when you get to the desired spot.
Excel usually comes as part of the Microsoft Office package—check under All Programs in your Start menu. If you intend to use this option you should have at least a basic understanding of Excel, as this will not be covered here.
Warning: Excel can cope with only columns of data or variables. Alternatively, you can use different Excel spreadsheets each with the ID as the first variable , convert each to SPSS separately, then merge the files in SPSS later see instructions in the next section.
Step 1: Set up the variable names Set up an Excel spreadsheet with the variable names in the first row across the page.
Step 2: Enter the data 1. Enter the information for the first case on one line across the page, using the appropriate columns for each variable. Repeat for each of the remaining cases. Remember to save your file regularly. Click on File, Save. Type in an appropriate file name. After you have entered the data, save your file and then close Excel. In the section labelled Files of type, choose Excel. Excel files have a. Find the file that contains your data. Click on it so that it appears in the File name section.
Click on the Open button. A screen will appear labelled Opening Excel Data Source. Make sure there is a tick in the box Read variable names from the first row of data.
The data will appear on the screen with the variable names listed across the top. You will then need to save this new SPSS file. Choose File, and then Save As from the menu at the top of the screen. Type in a suitable file name. In the Data Editor, Variable view, you will now need to define each of the Labels, Values and Measure information see instructions presented earlier.
You may also want to reduce the width of the columns as they often come in from Excel with a width of When you wish to open this file later to analyse your data using SPSS, make sure you choose the file that has a.
SPSS allows you to merge files by adding additional cases at the end of your file, or to merge additional variables for each of the cases in an existing data file e. This second option is also useful when you have Excel files with information spread across different spreadsheets that need to be merged by ID. To merge files by adding cases This procedure will allow you to merge files that have the same variables, but different cases; for example, where the same information is recorded at two different sites Creating a data file and entering data e.
The two files should have the same variable names for the data you wish to merge although other non-equivalent information can exist in each file. To do this, open one of the files, choose Transform from the menu, and then Compute Variable.
Click on the OK button, and then on OK in the dialogue box that asks if you wish to change the variable. This will create new ID numbers for this file starting at , and so on. Note this in your codebook for future reference. Then you are ready to merge the files.
Open the first file that you wish to merge. In the dialogue box, click on An external SPSS data file and choose the file that you wish to merge with. If your second file is already open it will be listed in the top box, An open dataset. Click on Continue and then on OK. Save the new data file using a different name File, Save As.
To merge files by adding variables This option is useful when adding additional information for each case with the matching IDs. Each file must start with the ID number. Go to the Data menu, choose Merge files and then Add Variables. In the Excluded variables box, you should see the ID variable listed because it exists in both data files.
If you have any other variables listed here, you will need to click on the Rename button to change the variable name so that it is unique. Click on the ID variable, and then on the box Match cases on key variables and on the arrow button to move ID into the Key Variables box. This means that all information will be matched by ID. Click on Continue and then OK. Save your merged file under a different name File, Save As.
I have highlighted a few of the main ones in the following sections. Sort the data file You can ask SPSS to sort your data file according to values on one of your variables e.
Click on the Data menu, choose Sort Cases and specify which variable will be used to sort by. Choose either Ascending or Descending. Split the data file Sometimes it is necessary to split your file and to repeat analyses for groups e. This procedure does not physically alter your file in any permanent manner. It is an option you can turn on and off as it suits your purposes. The order in which the cases are displayed in the data file will change, however.
You can return the data file to its original order by ID by using the Sort Cases command described above. Click on the Data menu and choose the Split File option.
Click on Compare groups and specify the grouping variable e. For the analyses that you perform after this split file procedure, the two groups in this case, males and females will be analysed separately.
Important: when you have finished the analyses, you need to go back and turn the Split File option off. Click on the first dot Analyze all cases, do not create groups.
Select cases For some analyses, you may wish to select a subset of your sample e. Click on the Data menu and choose the Select Cases option. Click on the If condition is satisfied button. Click on the button labelled IF. Creating a data file and entering data 4. Choose the variable that defines the group that you are interested in e.
Click on the arrow button to move the variable name into the box. Type in the value that corresponds to the group you are interested in check with your codebook. For example, males in this sample are coded 1, therefore you would type in 1. For the analyses e. Important: when you have finished the analyses, you need to go back and turn the Select Cases option off, otherwise it will apply to all analyses conducted.
Click on the Data menu and choose Select Cases option. Click on the first All cases option. This is particularly useful in the survey4ED.
In the following example, I will establish a set that includes only the demographic variables and the scale totals. Click on Utilities from the menu and choose Define Variable Sets. Choose the variables you want in your set from the list. Include ID, the demographic variables sex through to smoke number , and then all the totals at the end of the data file from Total Optimism onwards.
Move these into the Variables in Set box. In the box Set Name, type an appropriate name for your set e. Click on the Add Set button and then on Close. To use the sets you have created, you need to activate them. Click on Utilities and on Use Variable Sets.
To turn the option off 1. Data file comments Under the Utilities menu, SPSS provides you with the chance to save descriptive comments with a data file. Select Utilities and Data File Comments. Type in your comments, and if you would like them recorded in the output file, click on the option Display comments in output. Comments are saved with the date they were made. Display values labels in data file When the data file is displayed in the Data Editor window, the numerical values for all variables are usually shown.
If you would like the value labels e. To turn this option off, go to the View menu and click on Value Labels again to remove the tick. It is very easy to make mistakes when entering data, and unfortunately some errors can completely mess up your analyses.
For example, entering 35 when you mean to enter 3 can distort the results of a correlation analysis. So it is important to spend the time checking for mistakes initially, rather than trying to repair the damage later. Although boring, and a threat to your eyesight if you have large data sets, this process is essential and will save you a lot of heartache later!
First, you need to check each of your variables for scores that are out of range i. Step 2: Finding and correcting the error in the data file. Second, you need to find where in the data file this error occurred i.
To give you the chance to practise these steps, I have created a modified data file error4ED. In working through each of the steps on the computer you will become more familiar with the use of menus, interpreting the output from SPSS analyses and manipulating your data file.
Before you start, you should go to the Edit menu and choose Options. Under the Output Labels tab, go down to the final box Variable values in labels shown as: and choose Values and Labels. This will allow you to display both the values and labels used for each of your categorical variables—making identification of errors easier. Scores that fall outside the possible range can distort your statistical analyses—so it is very important that all these errors are corrected before you start.
To check for errors, you will need to inspect the frequencies for each of your variables. This includes all of the individual items that make up the scales. Errors must be corrected before total scores for these scales are calculated. It is a good idea to keep a log book where you record any errors that you detect and any changes that you make to your data file.
There are a number of different ways to check for errors using SPSS. I will illustrate two different ways, one that is more suitable for categorical variables e.
Checking categorical variables In this section, the procedure for checking categorical variables for errors is presented. In the example shown below, I will illustrate the process using the error4ED. Some deliberate errors have been introduced in the error4ED. Procedure for checking categorical variables 1.
From the main menu at the top of the screen, click on Analyze, then click on Descriptive Statistics, then Frequencies. Choose the variables that you wish to check e. Click on the arrow button to move these into the Variable box.
Click on the Statistics button. Tick Minimum and Maximum in the Dispersion section. Screening and cleaning the data Selected output generated using this procedure is displayed as follows.
There are two parts to the output. The first table provides a summary of each of the variables you requested. The remaining tables give you a breakdown, for each variable, of the range of responses. These are listed using the value label and the code number that was used if you changed the Options as suggested earlier in this chapter.
Do they make sense? Are they within the range of possible scores on that variable? You can see from the first table labelled Statistics that, for the variable Sex, the minimum value is 1 and the maximum is 3.
This value is incorrect, as the maximum value should only be 2 according to the codebook in the Appendix. For marital status, the scores are within the appropriate range of 1 to 8. The maximum value for highest educ is 22, indicating an error, as the maximum value should only be 6. Check the number of Valid and Missing cases. If there are a lot of missing cases, you need to ask why.
Have you made errors in entering the data e. If this occurs, open your Data Editor window, move down to the empty case row, click in the shaded area where the case number appears and press Delete on your keyboard.
Rerun the Frequencies procedure again to get the correct values. Other tables are also presented in the output, corresponding to each of the variables that were investigated.
In these tables, you can see how many cases fell into each of the legitimate categories. It also shows how many cases have out-of-range values. There is one case with a value of 3 for sex, and one person with a value of 22 for education.
We will need to find out where these errors occurred, but first we will demonstrate how to check for errors in some of the continuous variables in the data file.
Checking continuous variables Procedure for checking continuous variables 1. From the menu at the top of the screen, click on Analyze, then click on Descriptive statistics, then Descriptives. Click on the variables that you wish to check.
Click on the arrow button to move them into the Variables box e. Click on the Options button. You can ask for a range of statistics. The main ones at this stage are mean, standard deviation, minimum and maximum. Click on the statistics you wish to generate.
Screening and cleaning the data The output generated from this procedure is shown as follows. Do these make sense? In this case, the ages range from 2 to The minimum value suggests an error given this was an adult-only sample. Does the Mean score make sense? If there is an out-of-range value in the data file, this will distort the mean value.
If the variable is the total score on a scale, is the mean value what you expected from previous research on this scale? First, we need to find the error in the data file. I will illustrate two approaches. Method 1 1. Click on the Data menu and choose Sort Cases. In the dialogue box that pops up, click on the variable that you know has an error e. Click on either ascending or descending depending on whether you want the higher values at the top or the bottom. For sex, we want to find the person with the value of 3, so we would choose descending.
In the Data Editor window, make sure that you have selected the Data View tab so that you can see your data values. The case with the error for your selected variable e. Look across to the sex variable column. If this was your data, you would need to access the original questionnaires and check whether the person with an identification number of was a male or female. You would then delete the value of 3 and type in the correct value. Record this information in your log book.
When you find an error in your data file, it is important that you check for other errors in the surrounding columns. Shown below is another way that we could have found the case that had an error for sex. Method 2 1. Make sure that the Data Editor window is open and on the screen with the data showing. Click on the variable name in which the error has occurred e. Click once to highlight the column. Click on Edit from the menu across the top of the screen. By using our site, you agree to our collection of information through the use of cookies.
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