Hi,

I want to calculate whether the difference between the mean (and median) of COGS elasticity of the first and last (fifth) quintile of the variable CC_rank is significant. However, I don't know how to (1) calculate this and (2) how to interpret the outcome (where to find the t-statistic and where to find whether it is statistically significant)? See also the attachment. My dataset looks as follows:

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str24 gvkey double fyear str16 sic float CC byte CC_rank float(COGS_ELAST_w SGA_ELAST_w) double DemandUnc_w
"001013" 2010 "3661"      .083213 3         .          .                   .
"001161" 2010 "3674"     .0464763 2         .          .                   .
"001161" 2011 "3674"        .0484 2  .8325894  1.0834965                   .
"001161" 2012 "3674"        .0484 2         .          .                   .
"001161" 2016 "3674"          .01 1         .          .                   .
"001161" 2017 "3674"        .0036 1  .9103003    .763042                   .
"001161" 2018 "3674"        .0049 1  .8704142   .8210957  .05716461357229579
"001173" 2010 "3812"     .0465214 2         .          .                   .
"001173" 2011 "3812"    .01961911 1         .          .                   .
"001173" 2012 "3812"    .03151871 2         .   3.233185                   .
"001210" 2010 "4513"    .22369373 4         .          .                   .
"001210" 2011 "4513"    .22575164 4 1.0550966  -.1632245                   .
"001210" 2012 "4513"      .221005 4  .9377158  .04400323   .5803610081769496
"001210" 2013 "4513"     .2452515 5         .          .   .5803610081769496
"001210" 2014 "4513"     .2217242 4  .9452768  .13200726  .43110896032413987
"001210" 2015 "4513"    .11611764 4  .9242028   .4248407   .7402868053082245
"001210" 2016 "4513"    .21484175 4  -.847032 -1.1023777   2.172144231033772
"001210" 2017 "4513"    .13027234 4  .9137021   .4739289  2.3935216866991658
"001210" 2018 "4513"    .08727254 3  .9028409   .5478527   2.238168254026734
"001234" 2010 "3841"    .01985963 1         .          .                   .
"001234" 2011 "3841"   .016457789 1 -.2793875   .2906297                   .
"001239" 2010 "2844"    .05759989 2         .          .                   .
"001266" 2010 "0100"    .11921135 4         .          .                   .
"001266" 2011 "0100"    .12577406 4 .56089216  .18839873                   .
"001266" 2012 "0100"    .12941135 4  .8732479  -.3650734   .2965428658991338
"001266" 2013 "0100"     .1491128 4         .          .   .2965428658991338
"001308" 2010 "1381"    .09653551 3         .          .                   .
"001327" 2018 "3674"        .2209 4         .          .                   .
"001327" 2019 "3674"    .26009998 5         .          .                   .
"001439" 2010 "4955"  .0008999542 1         .          .                   .
"001439" 2011 "4955"  .0003999122 1  .8482099   .4419686                   .
"001468" 2010 "2771"    .03676287 2         .          .                   .
"001468" 2011 "2771"    .03742559 2  .8881156    .869736                   .
"001468" 2012 "2771"    .03189892 2  .8086588   .9599941  .38805648665823206
"001491" 2010 "2621"        .0049 1         .          .                   .
"001491" 2011 "2621"   .002500038 1  .9964366  .53563666                   .
"001491" 2013 "2621"   .003599904 1         .          .                   .
"001554" 2015 "3844"   .067571625 3         .          .                   .
"001562" 2010 "7372"   .011138536 1         .          .                   .
"001562" 2011 "7372"   .015645713 1  .5818798    .545915                   .
"001562" 2012 "7372"    .02348078 1         .          .                   .
"001562" 2013 "7372"   .012288558 1         . -.09442728   3.412793537597948
"001562" 2014 "7372"    .00881397 1 1.4814912  -.5438149  2.4343592195957373
"001562" 2015 "7372"   .005769911 1  .5633623  .51793754   2.192436310568739
"001562" 2016 "7372"   .007309522 1         .          .  2.2340672499335534
"001562" 2017 "7372"   .005353227 1         .   .4209529   1.963939500441383
"001562" 2018 "7372"   .005839577 1         .          .   .8023224776695616
"001585" 2010 "2870"    .10590045 3         .          .                   .
"001585" 2011 "2870"     .1121004 3   .867059   .6470457                   .
"001585" 2012 "2870"    .10370042 3  .7632479    .669174  .13552808042120704
"001602" 2010 "2836"     .3626603 5         .          .                   .
"001602" 2011 "2836"     .3606658 5  .7902785   1.028621                   .
"001602" 2012 "2836"     .3435637 5  .8299867   .8416294   .8183663690603937
"001602" 2013 "2836"     .3568908 5         .   .9439919   .6235664327598904
"001602" 2014 "2836"     .3959017 5  .5811682          .   .5243920727613531
"001602" 2015 "2836"     .4327322 5         .          .   .4775928940069547
"001602" 2016 "2836"    .45177975 5         .   .5466805  .10066452552318544
"001602" 2017 "2836"    .53243047 5         .          .  .07947048023957266
"001602" 2018 "2836"    .59016216 5   .768473    .953599  .24695015632388578
"001602" 2019 "2836"     .6104662 5         .          .   .2946093478598564
"001632" 2017 "3674"   .019599976 1         .          .                   .
"001632" 2019 "3674"    .10000005 3  .7769899   .7730811                   .
"001633" 2010 "3845"    .03690052 2         .          .                   .
"001633" 2011 "3845"     .0289996 2  .8402821   .7360951                   .
"001633" 2012 "3845"    .04400022 2   .832584   .3538707   .1070145572918289
"001633" 2013 "3845"    .04689984 2  .5822065   .7978694   .1975599254421822
"001633" 2014 "3845"    .06420007 3         .          .   .1975599254421822
"001633" 2015 "3845"    .06070021 3   .792922   .3263388   .3435673895256707
"001633" 2016 "3845"    .04339987 2         .          .   .3213443800766225
"001633" 2017 "3845"   .034000132 2         .          .   .2799902812023593
"001634" 2010 "7371"   .012102722 1         .          .                   .
"001634" 2011 "7371"   .016999707 1 -3.351743          .                   .
"001634" 2012 "7371"   .009799206 1         .          .                   .
"001635" 2010 "3663"    .03809475 2         .          .                   .
"001635" 2011 "3663"    .03323105 2  .7774491  .23374787                   .
"001635" 2012 "3663"    .03840341 2         .          .                   .
"001635" 2013 "3663"    .05416441 2  .6170333  -.2636976 .042752414430298556
"001659" 2010 "5150"   .006282527 1         .          .                   .
"001659" 2011 "5150"   .003188234 1  .9911377   .4569585                   .
"001659" 2012 "5150"   .004327188 1   .996388   .4541579  .37514235509970606
"001659" 2013 "5150"   .002810089 1  .9911712    .571389   .6371160473187414
"001661" 2010 "1381" 9.586567e-06 1         .          .                   .
"001661" 2011 "1381" 6.963934e-06 1  .9559199   .6582361                   .
"001678" 2010 "1311"        .0225 1         .          .                   .
"001678" 2011 "1311"         .029 2  .8195487   .5177277                   .
"001678" 2012 "1311"        .0569 2  1.559604   .8692445   2.488791635055578
"001678" 2013 "1311"        .0576 2         .          .   2.488791635055578
"001678" 2014 "1311"        .0361 2         .          .   2.488791635055578
"001678" 2015 "1311"        .0121 1         .          .   2.488791635055578
"001678" 2016 "1311"        .0585 3         .          .                   .
"001678" 2017 "1311"    .05834525 3         .   .7501639                   .
"001681" 2010 "3330"     .3589424 5         .          .                   .
"001681" 2011 "3330"    .07130198 3  .9148737          .                   .
"001681" 2012 "3330"    .03941382 2         .          .                   .
"001682" 2010 "1311"     .2901255 5         .          .                   .
"001682" 2011 "1311"     .1693205 4  .8959426          .                   .
"001682" 2012 "1311"     .1717091 4  .6700848   .7156118  .36639115206229805
"001682" 2013 "1311"    .18412916 4  .6155809          .   .3225365227824795
"001704" 2010 "3559"   .031699978 2         .          .                   .
"001704" 2011 "3559"     .0344105 2   .870629          .                   .
end
Thank you in advance!