Calculating the difference between maximum and minimum variable value over three overlapping years

[Hamza Almustafa]

Dear sata experts,

I have a panel data set ranging from 2010-2018 for all firms listed i the US market.

I am trying to calculate the difference between maximum and minimum ROA over three overlapping years, and not sure what is the right command to do this. Would appreciate any advice!

Thanks

[Phil Bromiley]

Having posted over 50 times, you should understand the FAQ on asking questions. Please read them. Note that posting pictures is strongly discouraged – not only can we not work with those numbers, we have trouble reading them. I can't even tell if your data are annual or not. These guidelines are to make it easier for us to help you.

I suspect what you want to do is after you have appropriately xtset your data, create a lead and lag value for ROA, and then use egen with rowmax to get the maximum ROA and egen with rowmin to get the min over the 3 year period.

If you had provided the appropriate data using dataex, then I might've programmed this for you.

If this is not annual data, then you should look at either statsby or user written rangestat.

[Hamza Almustafa]

Hi Phil, thanks for your replies and efforts understanding what i need. I will read the FAQ next time posting question carefully.

My data is annual unbalanced panel looks like the below table:

firmid	date	ROA
10043	17	0.23
10043	18	0.36
13944	17	0.15
27394	16	0.18

I need to generate a variable that consider the difference between the max and min of ROA over three overlapping years.

Thanks once again and sorry for any inconvenience.

Hamza

[Hamza Almustafa]

Here is the dataex

 No DataYear FirmROA
 1 2009     .177458693689945
 1 2010   .13660100950229914
 1 2011   .07814237265408061
 1 2012   .14186042905944918
 1 2013    .1742773063998069
 1 2014   .18942419471767397
 1 2015   .19638056464565778
 1 2016   .20806923166881067
 2 2009    .0879844632037548
 2 2010   .10316953256154864
 2 2011   .10796185957807884
 2 2012    .0840237599521784
 2 2013   .07039962449508282
 2 2014   .06201994434312046
 2 2015   .05819585927458937
 2 2016   .05527602836934021
 3 2009   .07760285074128807
 3 2010   .07721767767980453
 3 2011   .07199344464242503
 3 2012   .13609531975634778
 3 2013   .06537288119970874
 3 2014   .10157806321172656
 3 2015   .11655243569901982