To count the number of groups below a threshold in Excel, you can use the COUNTIF function. For example, if you have data in cells A1:A5 and you want to count the number of groups that are less than 3, you can use the following formula:

=COUNTIF(A1:A5,"<3")

This will return a value of 2, since there are two groups that are less than 3.

You can also use the COUNTIF function to count the number of groups that are greater than or equal to a certain threshold. For example, if you want to count the number of groups that are greater than or equal to 3, you can use the following formula:

=COUNTIF(A1:A5,">=3")

This will return a value of 3, since there are three groups that are greater than or equal to 3.