PLS 209                                                                                 Name___________________________
Research Methods
Homework6
Confidence Interval Using SPSS 

       COMPUTER INSTRUCTIONS

In carrying out the following instructions use the examples in your handout  titled "Computer Procedures for Using Political Science Data Sets."

    Step 1 Open PD01CFP in SPSS

• From the PLS 209 homepage Go to the SPSS Download Page
• On the SPSS download page click-on PD01CFP -- this is the comparative foreign policy data set under the International and Comparative Section
• Follow the directions on the download page for unzipping the file and opening it in SPSS

  Step 2 Use SPSS to generate descriptive statistics

• From the Data Editor Window select the Analyze Menu
• Select Descriptive Statistics on the Analyze Menu 
• Select Descriptives   
• Highlight the following variables and move them to the right window:  
      V6,  Military Expenditure
      V8, Population
      V9, Gross National Product
      V10 Level of Civil Strife
• Click on the Options Button
• Make sure mean,  std deviation, and S.E. of mean are checked 
• Click Continue
• Click OK

    Step 3 Print the table in the output window 

The table should contain the mean and standard error of the mean for each variable.

  QUESTIONS

    Once you have the printed output, do the following on the printed output.

      (1) Construct 95% confidence intervals for variables V6 & V8
           CI = mean +/- (1.96*SE)   [SE=standard error of the mean and is in the table you printed]

      (2) Construct two confidence intervals for V9
                  [Make sure you use the appropriate Z value ]
             a. The first is a 90% confidence interval
             b. The second is a 99% confidence interval

      (3) Construct two confidence intervals for V10
             a. The first is a 95% confidence interval using the displayed SE
             b. The second is a 95% confidence interval using one half the displayed SE

Return to PLS 209 Home Page