Hi,

Below is the example of my panel data. I want to generate a new variable (Increase) which is equal to Lag_inc in year t scaled by MV of t-1. I am not sure which code can recognize the year t and t-1 here.

I would be grateful if someone can help me to generate my variables.


Example:


. dataex firmid year Lag_inc MV

----------------------- copy starting from the next line -----------------------
Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str14 firmid int year float Lag_inc double MV
"SE0000101297" 2012         .    219.26579
"SE0000101297" 2013       -39    283.62315
"SE0000101297" 2014     -24.2    237.10895
"SE0000101297" 2015     -10.6    351.53292
"SE0000101297" 2016       -29    444.04799
"SE0000101297" 2017      -3.7   1049.62608
"SE0000101297" 2018        25   1049.62608
"SE0000101362" 2012         .    2282.8338
"SE0000101362" 2013       227   4326.84806
"SE0000101362" 2014       222   3392.64223
"SE0000101362" 2015       214   4720.19789
"SE0000101362" 2016       306   5226.64146
"SE0000101362" 2017       362    2533.5108
"SE0000101362" 2018       237   2641.54964
"SE0000101669" 2012         .            .
"SE0000101669" 2013         .            .
"SE0000101669" 2014         .            .
"SE0000101669" 2015         .            .
"SE0000101669" 2016         .            .
"SE0000101669" 2017         .            .
"SE0000101669" 2018         .            .
"SE0000101891" 2012         .            .
"SE0000101891" 2013         .            .
"SE0000101891" 2014         .            .
"SE0000101891" 2015         .            .
"SE0000101891" 2016         .            .
"SE0000101891" 2017         .            .
"SE0000101891" 2018         .            .
"SE0000102006" 2012         .            .
"SE0000102006" 2013   -19.753            .
"SE0000102006" 2014    10.518            .
"SE0000102006" 2015   104.637            .
"SE0000102006" 2016   395.412            .
"SE0000102006" 2017   203.781            .
"SE0000102006" 2018     -.459            .
"SE0000102824" 2012         .    618.10088
"SE0000102824" 2013      -356    692.08207
"SE0000102824" 2014     -28.8    797.08763
"SE0000102824" 2015       8.7    665.83068
"SE0000102824" 2016     173.9    522.64129
"SE0000102824" 2017      69.5    515.48182
"SE0000102824" 2018    -660.2    515.48182
"SE0000103699" 2012         .  77320.84573
"SE0000103699" 2013    2989.3 114690.62187
"SE0000103699" 2014  3257.142 113179.14659
"SE0000103699" 2015  3814.857 132390.76606
"SE0000103699" 2016 4583.1724 175355.58858
"SE0000103699" 2017  5493.434 176543.74011
"SE0000103699" 2018  6527.454 176543.74011
"SE0000103814" 2012         .  42097.18389
"SE0000103814" 2013      2362  78974.62991
"SE0000103814" 2014       671   58156.7575
"SE0000103814" 2015      2241  68942.22269
"SE0000103814" 2016      1566  78689.22424
"SE0000103814" 2017      4494  69727.40518
"SE0000103814" 2018      5745  69727.40518
"SE0000104788" 2012         .            .
"SE0000104788" 2013   154.684         5671
"SE0000104788" 2014   195.703      5363.81
"SE0000104788" 2015 212.08067      11844.8
"SE0000104788" 2016  259.1569   14206.6848
"SE0000104788" 2017  458.6677    12915.168
"SE0000104788" 2018   593.958    12915.168
"SE0000105116" 2012         .            .
"SE0000105116" 2013         .            .
"SE0000105116" 2014         .            .
"SE0000105116" 2015         .            .
"SE0000105116" 2016         .            .
"SE0000105116" 2017         .            .
"SE0000105116" 2018         .            .
"SE0000105199" 2012         .   3349.35973
"SE0000105199" 2013        50   5757.60552
"SE0000105199" 2014        35   2972.73682
"SE0000105199" 2015       102   5315.56287
"SE0000105199" 2016       189   3598.22717
"SE0000105199" 2017        88   2864.43637
"SE0000105199" 2018        74   2864.43637
"SE0000105264" 2012         .      38.8197
"SE0000105264" 2013  -115.297     48.94658
"SE0000105264" 2014   -73.238     48.94658
"SE0000105264" 2015   -58.987            .
"SE0000105264" 2016         .            .
"SE0000105264" 2017         .            .
"SE0000105264" 2018         .            .
"SE0000106205" 2012         .  14172.95995
"SE0000106205" 2013       730  20839.11801
"SE0000106205" 2014       298  20588.39967
"SE0000106205" 2015      1027  25234.06292
"SE0000106205" 2016       798  21237.31771
"SE0000106205" 2017      1727  24467.15978
"SE0000106205" 2018      2067  24467.15978
"SE0000106270" 2012         .  462261.6096
"SE0000106270" 2013     16867   568517.232
"SE0000106270" 2014     17093    451834.11
"SE0000106270" 2015     19976   379011.488
"SE0000106270" 2016     20898 202481.50848
"SE0000106270" 2017     18636    256536.16
"SE0000106270" 2018     16184    256536.16
"SE0000106320" 2012         .  30042.72298
"SE0000106320" 2013      1351  35758.29484
end
format %ty year
------------------ copy up to and including the previous line ------------------

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