Hello,

It appears that you are starting with a sorted table, so this should go swimmingly. You will be able to do this with a column formula for a column we will call "New_Time", but realize that unlike excel, where the first row could manually be set to zero, JMP requires all formulas within a column to be the same. The Lag function will be useful in this case and will behave like an Excel relative reference to the row above.

The graphic image from the formula editor for a column called "New_Time" is shown below.

This is described:

If the current row is == 1, OR if the current value of FID is different than the previous lag(FID,1), then the "time" of the current row is zero (reset). Else, add 20 to the prior value of the column New_Time (the cell above).

I have also included the JSL, that can be copied into the formula editor with a double click to JSL mode.

```
If( Row() == 1 | :FID != Lag( :FID, 1 ),
0,
Lag( :New_Time, 1 ) + 20
)
```

Notice that JMP comparison operators are double equals (vs excel single), and not equals in JMP is != (vs excel <>).

Good luck with this data preparation step, hope that the column formula enables all of the downstream analysis.

-G