SPSS Guide to Data Analysis Page 2 of9 Z-Scores Compared to a Population Mean and Standard Deviation: The methodology is the same except you need to tell SPSS what the population mean and standard deviation is(In the previous test,SPSS calculated it for you from the data it was given.Since SPSS cannot calculate the population mean and standard deviation from the class data,you need to plug these numbers into a formula). Remember the formula for a zscore is: X-4 2= You are going to transform the data you got into a zscore that is compared to the population by telling SPSS to minus the population mean from each piece of data, and then dividing that number by the population standard deviation.To do so,go to the DATA screen,then: Transform→Compute Name the new variable you are creating in the Target Variable box (ZUSPOP is a good one if you can't think of anything). Click the variable you want zscores for into the Numeric Expression box. Now type in the zscore formula so that SPSS will transform the data to a US population zscore.For example,if I am working with a variable called Sleep, and I am told the US population mean is 8.25 and that the US population standard deviation is.50,then my Numeric Expression box should look like this: (SLEEP-8.25)/.50 Compare for significance in the same way as above. For All T-Tests The significance that is given in the Output File is a two-tailed significance. Remember to divide the significance by 2 ifyou only have a one-tailed test! For One Group T-Tests Analyze→Compare Means→One-Sample T Test The Dependent variable goes into the Test Variables box. The hypothetical mean or population mean goes into the Test Value box.Be Careful!!!The test value should be written in the same way the data was entered for the dependent variable.For example,my dependent variable is "Percent Correct on a Test"and my population mean is 78%.If the data forSPSS Guide to Data Analysis Page 2 of 9 Z-Scores Compared to a Population Mean and Standard Deviation: · The methodology is the same except you need to tell SPSS what the population mean and standard deviation is (In the previous test, SPSS calculated it for you from the data it was given. Since SPSS cannot calculate the population mean and standard deviation from the class data, you need to plug these numbers into a formula). · Remember the formula for a z-score is: s - m = X z · You are going to transform the data you got into a z-score that is compared to the population by telling SPSS to minus the population mean from each piece of data, and then dividing that number by the population standard deviation. To do so, go to the DATA screen, then: Transform ‡ Compute · Name the new variable you are creating in the Target Variable box (ZUSPOP is a good one if you can’t think of anything). · Click the variable you want z-scores for into the Numeric Expression box. Now type in the z-score formula so that SPSS will transform the data to a US population z-score. For example, if I am working with a variable called Sleep, and I am told the US population mean is 8.25 and that the US population standard deviation is .50, then my Numeric Expression box should look like this: (SLEEP – 8.25)/.50 · Compare for significance in the same way as above. For All T-Tests · The significance that is given in the Output File is a two-tailed significance. Remember to divide the significance by 2 if you only have a one-tailed test! For One Group T-Tests Analyze ‡ Compare Means ‡ One-Sample T Test · The Dependent variable goes into the Test Variables box. · The hypothetical mean or population mean goes into the Test Value box. Be Careful!!! The test value should be written in the same way the data was entered for the dependent variable. For example, my dependent variable is “Percent Correct on a Test” and my population mean is 78%. If the data for