I have a question regarding confidence intervals in SPSS. My understanding is that a 95% confidence interval (the one I'm planning to use) is bounded by values that are 1.96 standard deviations above and below the mean. However, when I have SPSS calculate the 95% confidence interval for my data, the bounds shown in the descriptives table don't make any sense. Sometimes the bounds will be less than one standard deviation from the mean; sometimes they will be several standard deviations from the mean. My data are all clean, so I doubt that's the problem.

I'm wondering what's going on here...how does SPSS calculate confidence intervals? Is there something I'm missing?

Thanks so much!!