Joining with `by = join_by(FQINSTID, PHASE, SAMPLE, COUNTRY, YEAR, PERSONID,
ELIGIBLE, EAID, CONSENTFQ, INTFQMON, INTFQYEAR, CONSENTHQ, SURVEYWILLING,
FQWEIGHT, HQWEIGHT, STRATA, URBAN, SEX, MARSTATHQ, AGE, BIRTHMO, DOBCMC,
PREGNANT, EDUCATTGEN, MARSTAT, PTR1STAGE, WIVESOTH, COHAB1STSTARTMO,
COHAB1STSTARTYR, COHABLASTSTARTMO, COHABLASTSTARTYR, COHAB1STSTARTCMC,
COHABLASTSTARTCMC, WEALTHQ, SCORE, ROOF, ELECTRC, BIRTHEVENT, AGE1STSEX,
TIMESINCESEX, TIMESINCESEXVAL, TIMESINCESEXDAY, KID1STBIRTHCMC, LASTDOBCMC,
FERTPREF, PGDESIRE, PREFTIMECH, PREFTIMECHVAL, PREFTIMECHMONTH, FERTPREFNPREG,
FERTPREFPREG, STARTKIDDEC, NEXTKIDDEC, STARTKIDDECWILL, PTRDISCKIDSTART,
FPPROVIDERGEN, FPPROVIDER, CP, MCP, TCP, FPCURRUSE, FPCURREFFMETH,
FPCURREFFMETHRC, FPNOWUSINJ, FPNOWUSEMRG, FPNOWUSCON, FPNOWUSFC, FPNOWUSCYCB,
FPNOWUSRHY, FPNOWUSWD, FPNOWUSTRAD, FPDECIDER, CONFPARTNERTALK, FPCANSWITCH,
FPUSPLAN, FPUSPLAN_NPREG, FIRSTCARRIEDAWAY, FIRSTCURIOUS, FIRSTFORCE,
FIRSTEXPECT, FIRSTTIMING, FIRSTWILLING, FIRSTSUB, HHDECMED, wantanotherchild,
pregnant, maritalstatus, agegroup, usingmoderncon, educationlevel,
decidemedical, decidefp, censored, birtheventvar, parity)`