Creating loop and generating change variable for multiple variables

[Jake Magel]

Hello,

I am trying to create change scores (T1 - T0 ) for multiple variables and just add the extension _dlt1 to the end of each variable to delineate that it is a variable representing a change score. I am a bit lost in how to create this loop so not really sure where to start. I appreciate any suggestions. Below is the data.

* Example generated by -dataex-. For more info, type help dataex
clear
input byte record_id float(time_rc dd1_knowledge_rc dd2_causes_rc dd3_physical_rc dd4_psych_rc dd5_riskfactors_rc dd6_counsel_rc dd7_advise_rc dd8_questrights_rc dd9_askinfo_rc dd10_persondiff_rc dd11_personrespon_rc dd12_approach_rc)
 1 0 3 6 5 6 3 6 6 2 2 6 6 6
 1 1 2 2 2 2 2 2 2 2 2 2 2 2
 2 0 5 5 6 5 6 6 6 4 4 5 6 5
 2 1 3 3 2 4 2 3 3 2 2 4 4 4
 3 0 6 6 7 7 7 7 7 1 1 2 2 2
 3 1 1 1 1 1 1 1 1 1 1 1 1 1
 4 0 3 4 3 3 4 5 4 4 4 3 4 4
 4 1 2 2 2 2 2 3 3 3 3 2 2 2
 5 0 4 6 4 5 6 5 5 2 4 3 6 5
 5 1 2 3 3 3 2 3 2 1 1 1 2 2
 6 0 2 3 5 5 3 6 2 2 3 2 2 1
 6 1 2 2 2 2 2 3 2 2 2 1 1 1
 7 0 5 5 5 3 3 6 6 3 3 3 3 3
 7 1 2 2 2 2 2 2 2 1 1 1 1 1
 8 0 3 4 4 5 3 5 5 1 1 7 2 6
 8 1 1 1 1 1 1 2 2 1 1 3 2 2
 9 0 3 4 5 5 3 5 5 2 3 6 6 6
 9 1 3 3 3 3 3 4 3 2 2 5 4 4
10 0 3 5 6 6 5 5 6 1 2 1 2 3
10 1 2 3 3 3 3 3 3 1 1 1 2 2
11 0 5 6 . 6 5 6 6 5 5 6 6 6
11 1 1 1 1 1 1 2 2 1 1 2 2 1
12 0 5 5 3 4 5 6 5 2 2 2 3 4
12 1 2 2 2 2 2 3 2 1 1 1 1 1
13 0 4 3 3 3 1 5 5 2 2 1 2 4
13 1 2 1 2 3 3 3 2 2 2 3 3 3
end

[Clyde Schechter]

xtset record_id time_rc
foreach v of varlist dd* {
    gen `v'_dlt1 = D1.`v'
}

[Jake Magel]

Thank you, Clyde. Works great. Can you please explain how D1.`v' executes the subtraction between the variables?

[Clyde Schechter]

See -help fvvarlist-.

[Jake Magel]

Thank you.