DiD estat trendplots Error

[Cecilia Fiori]

Hi, I am writing my Master's thesis using a DiD design to establish whether extreme weather events influence party vote shares in 93 electoral districts within the state of New South Wales, Australia.

I have a 3 waves panel data from 2011, 2015 and 2019 - where treatment occurs in 2019 - as follows:

* Example generated by -dataex-. For more info, type help dataex
clear
input long id int year double(GRN_vc ALP_vc CDP_vc INF_vc) byte treated
 1 2011  .08387307462036685 .20981875578294237   .03423501877755402  .07105535296358788 0
 1 2015  .13861543347094316  .6142690801312586   .06303588440774849  .14459616809569176 0
 1 2019  .10239012676606914  .2700340648908248  .027670743284748982  .09487909755961356 1
 2 2011  .08387307462036685 .41377991345717086   .03803581247459896  .10621817399411891 0
 2 2015  .13861543347094316  .6659801264679314  .061860885275519424   .1277687443541102 0
 2 2019  .10239012676606914  .4779970760233918   .02867933723196881  .11829922027290449 0
 3 2011  .13861543347094316 .16737507775243624  .027057847812564793  .04457806344598798 0
 3 2015  .13861543347094316 .41314537568210435   .03372044214355674  .07226808451098363 0
 3 2019  .13861543347094316 .27241254468932435   .02036475539666018  .04984839570982486 0
 4 2011  .08387307462036685 .23536568246689438  .010130550746338497  .04445276309016892 0
 4 2015  .08387307462036685  .4162042895616341  .013173691553911548 .052143158441221325 0
 4 2019  .08387307462036685  .3351045235265329  .007108065906919294  .03442168309678622 0
 5 2011  .05894108421239028 .39672661961498573  .045407401785940146  .12830436872328047 0
 5 2015 .059581158838485214  .6877759935768768   .05315803559480797   .1481332798073063 0
 5 2019 .057137098805864865  .5129994457600645  .028492971229908803  .14455585226986448 0
 6 2011  .03500990846465981 .18873266018684534   .02912774055550313  .05715454059324966 0
 6 2015  .11071749326414529  .6423011675481489   .05857698832451851   .1479393274124339 0
 6 2019 .044201135442011354 .36824448868244486  .025989825259898253  .10318513603185137 0
 7 2011  .08898842658519535  .2658778448074981  .026176112678973667  .05201563835020583 0
 7 2015   .1736752608116182  .6389080380532194   .04761248219127717   .1158141458706742 0
 7 2019  .08101883965483754  .3185261230265531   .02341777420160373  .09003634749313282 0
 8 2011  .09682601611089436  .1673054414430955  .047139283501250774  .04266403506758772 0
 8 2015  .19360766189654213   .546801046828888   .09298958739350743  .11531822484548138 0
 8 2019  .08442634267568687  .2428551705094574   .03849693957384141  .05370702747480326 0
 9 2011  .14880531214281825 .23237903445272956  .020600881728623524 .059190115930985686 0
 9 2015  .21801312514143473  .6152070604209097   .03113826657614845  .11016066983480426 0
 9 2019  .12410727299227518  .3391390953699655   .01464801049409707  .07909439828985085 0
10 2011  .05935044788069859 .41029875394084975    .0607516388930591  .08104388730420858 0
10 2015  .07631328252585738  .6800149700598802   .07709580838323353   .1220059880239521 0
10 2019  .07118199914329629  .5051276236551012   .04986519515206491  .10348476831204173 0
11 2011   .2629617587474677  .2322236950704049  .053147587724783035  .03796613560763325 0
11 2015   .3105217542035015  .5490032934650719  .061813139192234356  .06534928063789218 0
11 2019  .18258846577690707  .4272560303661075  .041973796987878044 .049810211828088646 1
12 2011  .07858207804226004 .20387126625880417  .027376484499511595   .0493290833376176 0
12 2015 .043911439114391146  .7273062730627307   .05178351783517835   .1173739237392374 0
12 2019  .06820748324926598  .5502020125975557  .035283194057567316   .1375944189314663 0
13 2011  .06882448346378958 .44171779141104295  .026302799520485157  .09573842935383024 0
13 2015  .10150533138197784  .6165586452017562   .07113736148860547  .14744929960275976 0
13 2019  .05520998580612841  .3342448025381982  .028867830007514403  .09100776488269183 0
14 2011  .06074243456261555 .25114332976549575   .03303493237326068  .06076676072783886 0
14 2015  .07852797372448027  .7093643862202814   .05326017989773448  .11984473556525958 0
14 2019  .06619248476828495  .5088909105946572  .041656328398533345  .10738014501144101 0
15 2011  .07432489156289353 .36177417098083114   .04371064782426193  .07992164544564152 0
15 2015  .13329596063409013  .6108879130461864   .07315705876856957   .1355694665047183 0
15 2019  .11730697500932488  .4498787765759045   .03639033942558747  .10886795971652369 0
16 2011   .1584559163659913 .35826625959848274  .029951891941900267  .08347210657785178 0
16 2015  .19521828055575147  .5068058396219761   .10177022357006842  .13393046054023555 0
16 2019  .07080117114719191 .20235560287463403   .03105314523999645  .05243545381953686 0
17 2011  .08153877376147203  .1511037950706925    .0393938710623041 .036191850632511784 0
17 2015  .09349044499966237  .7516037544736309  .028901343777432642  .10037814842325613 0
17 2019  .08358068184970457  .5435102221975644  .019362534328275404   .1010014147410469 0
18 2011  .10423751686909581 .42496626180836705  .030742240215924428  .08950067476383265 0
18 2015  .16809939556749495  .6649764942914708  .036937541974479515  .10782404298186703 0
18 2019  .12682118386227026 .46065748138620227   .02288074801494051  .07329260147920943 0
19 2011   .1259625239809729  .3084807232398623   .02509789493048803 .062468791884575964 0
19 2015      .1984558454018  .5976974736168852  .059116451185526976  .12024304445155101 0
19 2019  .10950379387521153   .296195207161963   .02953217970413232  .08166384627981876 0
20 2011  .10232496346485984    .20438421681945  .032336920419821974 .056915105619768834 0
20 2015   .2477768983658457  .5320545649238791   .07667954746496577  .11606685599888263 0
20 2019   .1397749834546658 .28955658504301784  .032111184645929845  .08031767041694242 0
21 2011   .1339757845317519 .18715097603162836    .0383493946132938 .054138868297504326 0
21 2015   .3831039593478721 .49769214482320556  .017361846284141436  .07355494389159432 0
21 2019   .1922368321429473  .3462887716730182 .0072432677990056284  .04308103879060142 0
22 2011   .2532732717867485 .20508378090735838  .012523822488429077 .040714798406058954 0
22 2015  .08470853615101508  .6628873323044046   .06713759943013178  .14697851121928054 0
22 2019  .03888034086874186 .24855012427506215  .024766244525979406  .09069120605988874 1
23 2011  .08855183580170484  .1738178008476594  .034073051097671316  .04943092528215629 0
23 2015   .2161597156893488  .5270199644611686   .08043273753527752  .13588376711612835 0
23 2019  .08791056497436134 .23890146440615329  .021735113410634267 .060562664572458076 0
24 2011   .1262233016644046 .08052956163535491  .022358739909993573 .036740719575207755 0
24 2015   .3974358974358974  .3828218413710642  .062309020858243656  .10814401487976617 0
24 2019  .14584073311074802 .15500461746110678  .020482583883876773  .04392507873363169 0
25 2011    .124570834839176 .22757047343693532   .02139049512106975  .05088995301770871 0
25 2015  .25369606758523583  .5300211203862013  .039676154078246005  .12375540581313486 0
25 2019  .11526532590259268  .2726920281075842  .016719166464744365  .06014053792100799 0
26 2011 .049691741856957634  .1748471939248009   .04622549149313365  .06448284073770275 0
26 2015  .10841195412688549   .625783854019547   .08282017965086719  .14564148918140218 0
26 2019 .057748062244837584 .27811963789124905   .03591503461333649  .10463877877048695 0
27 2011   .0649546827794562  .3519125403246454   .04862000102411798  .07616877464283886 0
27 2015  .08240772548570556  .6682316118935837   .07588075880758807  .12950875987633115 0
27 2019  .05802309424560395  .4143069330650184   .04285851181064635   .0985098941114465 0
28 2011   .1495206753469738 .16979062336051892   .04757476033767349    .037201316354271 0
28 2015   .3135040635040635 .45601020601020603   .09610659610659611  .09350784350784351 0
28 2019  .12072966204884325 .26677694304684446   .04335240195740575  .04457003698853585 0
29 2011  .06335347575771993  .3993909692153971   .05462244849407622  .11854689061236143 0
29 2015   .0475268491907427  .6463772500378158   .10591438511571623  .13674179397973074 0
29 2019 .062468050301605155  .5282690931397608   .04237807995092526   .1374603823739904 0
30 2011   .1319585608973574 .27895471577967723   .03105483578653474  .05740736205334182 0
30 2015  .17441100734078943  .6602098466505246   .03781851723740343  .10365502133056613 0
30 2019  .10830588176125934  .4095606910252219  .022782709281565117  .08358689365554355 0
31 2011  .11731334738595259 .19699690321909075   .04244411481510396  .05701720144689931 0
31 2015  .17073170731707318  .6495218047865282   .05175490779298037  .10497414542625727 0
31 2019  .09783289817232375  .3522976501305483  .021879895561357703  .07091383812010443 0
32 2011 .061003109497021056    .34771772413302   .04809038904317691  .09584846542761519 0
32 2015  .07424805185347025  .6061102614521885   .13440390357585028    .143543805986454 0
32 2019  .05413227300181196  .4527884034628548  .036214012482383734  .11979061807932354 0
33 2011  .07758040171833275 .10974108905143388   .03367003367003367 .039916405433646815 0
33 2015  .19815504701082137  .5164094376441369   .07864703447460233  .16149251966175862 0
33 2019  .08357907383136741  .2368665356050677  .030935998252512014  .08281454783748361 0
34 2011  .17522642793571017 .23443798753991937   .04143762106695985 .048060310978482804 0
end
label values id id
label def id 1 "Albury", modify
label def id 2 "Auburn", modify
label def id 3 "Ballina", modify
label def id 4 "Balmain", modify
label def id 5 "Bankstown", modify
label def id 6 "Barwon", modify
label def id 7 "Bathurst", modify
label def id 8 "Baulkham Hills", modify
label def id 9 "Bega", modify
label def id 10 "Blacktown", modify
label def id 11 "Blue Mountains", modify
label def id 12 "Cabramatta", modify
label def id 13 "Camden", modify
label def id 14 "Campbelltown", modify
label def id 15 "Canterbury", modify
label def id 16 "Castle Hill", modify
label def id 17 "Cessnock", modify
label def id 18 "Charlestown", modify
label def id 19 "Clarence", modify
label def id 20 "Coffs Harbour", modify
label def id 21 "Coogee", modify
label def id 22 "Cootamundra", modify
label def id 23 "Cronulla", modify
label def id 24 "Davidson", modify
label def id 25 "Drummoyne", modify
label def id 26 "Dubbo", modify
label def id 27 "East Hills", modify
label def id 28 "Epping", modify
label def id 29 "Fairfield", modify
label def id 30 "Gosford", modify
label def id 31 "Goulburn", modify
label def id 32 "Granville", modify
label def id 33 "Hawkesbury", modify
label def id 34 "Heathcote", modify

In order to get an estimate of any party voteshare, I coded in Stata 17:
xtdidregress (GRN_vc) (treatment), group(id) time(year)
estat trendplots, omeans

The estat trendplots shows
treatment assignment times vary; not allowed with estat trendplots
r(459);

However, my treatment assignments times do not vary : treatment happened in 2019 for all districts that were affected.

Could you please provide me with some clarity as to what I am missing?

Many thanks for your time and help !

[Øyvind Snilsberg]

what does Stata return if you type -display e(tmin)- after running the regression?

[Cecilia Fiori]

Stata displays 2011 if I type -display e(tmin)- after running the regression.

[Øyvind Snilsberg]

so at least one district is recorded as treated before 2019. to see all districts that are treated before 2019 and in which year(s) type -tab id year if treated & year < 2019-

[Cecilia Fiori]

Works now !! Thank you so much

[Cecilia Fiori]

Hi again, I am having the same problem with another dataset with the same structure for which I have 5 years - from 2004, 2008, 2012, 2016 and 2020. Treatment happens in 2012 for which I code a dummy in 2012 (1 in 2012, 0 other years).
I type :
didregress (GRN_vc) (treatment), group(id) time(year)
estat trendplots, omeans

for which Stata returns the same error message : "treatment assignment times vary; not allowed with estat trendplots
r(459);".

I checked the problem with -display e(tmin)- for which i get 2012 and the data is perfectly clean. Yet the parallel trends graph will not appear.

Again, am I missing something? Please let me know!
Best,