Doing t-tests by hand

Four steps Set up null and alternative hypothesis Directional? Non-directional? Determine t-critical from table One-sample? Independent sample? Dependent (or paired sample)? Compute t-obtained Compare t-obtained to t-critical. If t-obtained is larger then you have significance

Formula for one sample t obtained = Sample mean – Population mean / standard error of mean

Independent samples t obtained = M1 – M2 / standard error of difference between the means

Dependent or Paired Samples Be sure to work with the Differences between your paired scores – NOT the original scores t obtained = mean of differences / standard error of mean of differences