You are calculating a two-sided confidence interval for the mean using the quantile from the t distribution for (1-alpha)% confidence and (n-1) degrees of freedom. The function for this in JMP is t Quantile( probability, df ). Here is the quantile for a two-sided 95% confidence interval for the mean:
![Capture.JPG Capture.JPG](https://community.jmp.com/t5/image/serverpage/image-id/5511iBC75C8FB10C35DD5/image-size/large?v=v2&px=999)
I used the script editor and an embedded log but you could also enter it into a column as a formula. This quantile is correct.
If you enter your 4 observations into a column, then select Analyze > Distribution, select the data column and click Y, Columns, then click OK. You will find the 95% CI in the Summary Statistics report.
Here is an example of 4 observations:
![Capture.JPG Capture.JPG](https://community.jmp.com/t5/image/serverpage/image-id/5512iB20D0D1B21D46E79/image-size/large?v=v2&px=999)
Here is the Summary Statistics report for them:
![Capture.JPG Capture.JPG](https://community.jmp.com/t5/image/serverpage/image-id/5513i7FDCE3C5D5A2037A/image-size/large?v=v2&px=999)