Unable to do rare events T-Chart; restricted by number of rows

[#1]

Data set with 300 rows. A column with time between events. Control chart builder doesn't let choose rare events, e.g. T Chart. Only when deleting rows (not just hide & exclude) leaving about 25 rows can rare event be selected.

Many thanks,

[#2 · Accepted solution]

How does your data look like (could it be the issue)? For example could you have missing or negative values on your subgroup column?

I managed to create T-chart with 400 rows with no issues (using JMP18)

[#3]

Thanks. There are no missing nor negatives (nor zeros),