SPSS - Quick Primer
While there are various SPSS help resources that will be made available to you (eg Steve Jost's, Prof Sabatini's, etc), this file is intended as a very quick primer on the basic things you'll need to do to get started using SPSS.
Opening files from your textbook in SPSS: Your textbook uses files with the extension 'POR': However, SPSS defaults to looking for files with an extension of 'sav'. What this means is that after clicking on File >> Open, you will need to change the 'Files of Type' option away from 'sav' to 'por'. For this problem, and any subsequent problem that asks you to draw a graph, be sure to paste your graph into your Word document.
Reminder on drawing a scatterplot:
1. From the 'Data Editor' view, choose: Graphs >> Legacy Dialogs >> Scatter/Dot
2. Choose Simple Scatter, and click 'Define'
3. Remember to put your explanatory variable on the x-axis and your response variable on the y-axis
4. Click OK
To generate a line:
1. In the 'Statistics Viewer' view, double click the graph
2. This will bring up the 'Chart Editor' view.
3. Look for the little icon of a scatterplot with a line through it. You'll know you're on the correct icon if, when you hover over it for a second, you see the label 'Add Fit Line to Total'
4. In the 'Fit Line' tab, choose 'Linear' (since you are trying to see if there may be a linear relationship), and click Close.
5. You can close the 'Chart Editor' view. You will now see a line in the 'Output' view.
It probably wouldn't hurt to go through this process 2-3 times to get comfortable since you'll be doing it so much. I'd begin all the way at the beginning. In other words, re-open a data file and go through the whole thing again until you're comfortable opening files and creating a scatter plot. Other graphs have their own sequence of commands, but are often similar to scatterplots.
Correlation ('r'): Analyze >> Correlate >> Bivariate. Choose your variables, and click on OK.
Drawing a histogram: Graphs >> Legacy Dialogs >> Histogram à select your field.
Plotting a curve over a histogram: Click on the histogram to open the ‘Chart Editor’. Click the icon that shows a curve (hovering will display the label ‘Show Distribution Curve’)
Boxplots: Graphs >> Legacy >> Boxplots. Choose ‘Summaries of SEPARATE variables’
Finding descriptive statistics such as mean, median, standard deviation etc: Analyze >> Descriptive Statistics >> Descriptives (for things like mean, media, SD). You can select which stats you want by choosing ‘Options’.
Regression Analysis: Analyze >> Regression >> Linear. Choose your explanatory and response variables. (At this point, you need to decide if you are also interested in the residuals. If so, click: Save, then under Residuals, select ‘Standardized’ and click Continue.) Then click OK. You will see a few tables. The ‘Model Summary’ table gives you r and r2. The correlation table gives you the y-intercept just under the column labeled ‘B’. The value below that is the slope.
Residuals: For residual analysis, see ‘Regression Analysis’. This step adds an additional column in the Data Editor view that shows the residual for each datapoint. Then proceed as though you were creating a scatterplot: Graph >> Legacy >> Scatterplot, choose ‘Simple Scatter’ and click Define. In this case, however, you place the Residual column on the y-axis (instead of the response variable).
Incidentally, you will notice that the residual line does not give you the 0-axis line that we have seen in our examples. To get one, double-click the graph, and look for the little icon that shows a straight horizontal line. (Hovering will display: “Add a reference line to the y axis”). When the ‘Properties’ window appears, you can type 0 under ‘Position’ assuming that is where you want the line. Click ‘Close’.
Plot: Recall that plotting two quantitative variables using this plot can
give you an idea whether the data follows a "Norma"
you ca do things such as calculate z-scores, etc). To plot in SPSS:
Analyze >> Desc Stats >> P-P Plot. Simply choose your variable and
Stemplot: Analyze >> Descriptive Statistics >> Explore. Choose the variable you want to plot. Click on 'Plots' >> check Stem and Leaf. Click Continue, click OK.
Confidence Intervals: Analyze >> Descriptive Statistics >> Explore. Choose your variable. Click on ‘Statistics’ à enter the confidence level (e.g. 95) à click ‘Continue’ >> OK.
files between the local machine and the remote machine: Recall
that you will want to somehow copy all of the files from the book's CD onto the
remote computer. Review the steps discussed in lecture on how to do this. Vert
briefly, it involves changing the settings when you start Remote Desktop. Be
sure that the 'Options' button is selected so that you can see all of the tabs.
Choose: Local Resources tab >> under 'Local devices and resources' click
on 'More' >> click on the plus sign next to 'Drives' >> select the
drive(s) you want to be able to access from the remote machine. Note that these
drives will show up only when you navigate up to the folder/directory
level that shows all of the drives on your computer.
Random Tip: If you get tired of having to always choose 'POR' file, you can try the following: Rename all of the files from their POR extension to SAV. The easiest way to do this is from the command line (for those of you wh know how to use it). As far as I can tell, this does not harm the data.