Independent Samples t-Test With SPSS
For this research we are interested to show the basic skills of hypothesis testing using SPSS 17 Statistical Software. We are given with the data set and should perform independent samples Student’s t-test via SPSS. To do this, one variable should be chosen as quantitative and one variable must be a factor variable. These two variables will be Age and Sex.
The null hypothesis is: There is no significant difference in age between males and females
The alternative hypothesis is: There is a significant difference in age between males and females.
H0: μ1=μ2Ha: μ1≠μ2
This will be a two-tailed test.
Set the level of significance alpha:
α=0.05
Run SPSS for Age by Sex:
Syntax:
T-TEST GROUPS=SEX(1 2) /MISSING=ANALYSIS /VARIABLES=AGE /CRITERIA=CI(.95).
The obtained p-value of the test is 0.442. This value is higher than alpha level. That’s why we failed to reject the null hypothesis. We have no evidence to claim that there is a significant difference in age between males and females (at 5% level of confidence).
The 95%-CI is (-2.353, 1.028). This confidence interval may be interpreted in the following way: we are 95% confident that the true mean difference is between -2.353 and 1.028. Since 0 value is within this interval, null hypothesis is approved.
Sources
Argyrous, G. Statistics for Research: With a Guide to SPSS, SAGE, London, ISBN 1-4129-1948-7
