Confidence Interval in the Oneway Anova

[#1]

Hello,

I'm using the "Big Class" data table to run the Oneway ANOVA analysis for "height" and notice that the confidence interval values are different between the "Means for Oneway Anova" table and "Means and Std Deviations" table.

My calculation is the same as the "Means and Std Deviations" table, but am trying to understand why they are different from the other table.

[#2 · Accepted solution]

The first result, as noted at the bottom of the first table, uses the pooled estimate of the standard error of the mean. The second table computes statistics, including the standard error, separately for each level of the categorical factor. That is, the estimates of the standard error in the second table are not pooled.