COMLEX LEVEL 1 BIOSTATS (FIRST
AID) EXAM QUESTIONS AND
ANSWERS
odds1Lratio1L-1LANS--OR1L=1Lad/bc1L
Typically1Lused1Lin1Lcase-control1Lstudies
Relative1LRisk1L-1LANS--RR1L=1L[a/(a1L+1Lb)]1L/1L[c/(c1L+1Ld)]
Typically1Lused1Lin1Lcohort1Lstudies
Relative1LRisk1LReduction1L-1LANS--RRR1L=1L11L−1LRR
Risk1Lof1Lexposed1Lgroup1Lover1Lrisk1Lof1Lthe1Lcontrol1Lgroup
Attributable1LRisk1L-1LANS--AR1L=1L[a/a1L+1Lb]1L−1L[c/c1L+1Ld]
The1Ldifference1Lin1Lrisk1Lbetween1Lthe1Lexposed1Land1Lcontrol1Lgroups
Absolute1LRisk1LReduction1L-1LANS--ARR1L=1L[c/c1L+1Ld]1L−1L[a/a1L+1Lb]
The1Ldifference1Lin1Lrisk1Lattributable1Lto1Lthe1Lintervention1Las1Lcompared1Lto1Lthe1Lco
ntrol
Number1LNeeded1Lto1Ltreat1L-1LANS--NNT1L=1L1/ARR
Number1Lof1Lpatients1Lwho1Lneed1Lto1Lbe1Lexposed1Lfor1Lone1Lpatient1Lto1Lbenefit
Number1LNeeded1Lto1LHarm1L-1LANS--NNH1L=1L1/AR
Number1Lof1Lpatient1Lwho1Lneed1Lto1Lbe1Lexposed1Lto1La1Lrisk1Lfactor1Lfor1Lone1Lto1Lbe1
Lharmed
Case1LFatality1LRate1L-1LANS--CFR%1L=1L(deaths/cases)1Lx1L100
Percentage1Lof1Ldeaths1Loccurring1Lamong1Lthose1Lwith1Ldisease
Mortality1LRate1L-1LANS--
Number1Lof1Ldeaths1Lwithin1La1Lpopulation1Lover1La1Lperiod1Lof1Ltime.1LUsually1Lgiven1Li
n1Ldeaths1Lper1L1,0001Lper1Lyear.
AID) EXAM QUESTIONS AND
ANSWERS
odds1Lratio1L-1LANS--OR1L=1Lad/bc1L
Typically1Lused1Lin1Lcase-control1Lstudies
Relative1LRisk1L-1LANS--RR1L=1L[a/(a1L+1Lb)]1L/1L[c/(c1L+1Ld)]
Typically1Lused1Lin1Lcohort1Lstudies
Relative1LRisk1LReduction1L-1LANS--RRR1L=1L11L−1LRR
Risk1Lof1Lexposed1Lgroup1Lover1Lrisk1Lof1Lthe1Lcontrol1Lgroup
Attributable1LRisk1L-1LANS--AR1L=1L[a/a1L+1Lb]1L−1L[c/c1L+1Ld]
The1Ldifference1Lin1Lrisk1Lbetween1Lthe1Lexposed1Land1Lcontrol1Lgroups
Absolute1LRisk1LReduction1L-1LANS--ARR1L=1L[c/c1L+1Ld]1L−1L[a/a1L+1Lb]
The1Ldifference1Lin1Lrisk1Lattributable1Lto1Lthe1Lintervention1Las1Lcompared1Lto1Lthe1Lco
ntrol
Number1LNeeded1Lto1Ltreat1L-1LANS--NNT1L=1L1/ARR
Number1Lof1Lpatients1Lwho1Lneed1Lto1Lbe1Lexposed1Lfor1Lone1Lpatient1Lto1Lbenefit
Number1LNeeded1Lto1LHarm1L-1LANS--NNH1L=1L1/AR
Number1Lof1Lpatient1Lwho1Lneed1Lto1Lbe1Lexposed1Lto1La1Lrisk1Lfactor1Lfor1Lone1Lto1Lbe1
Lharmed
Case1LFatality1LRate1L-1LANS--CFR%1L=1L(deaths/cases)1Lx1L100
Percentage1Lof1Ldeaths1Loccurring1Lamong1Lthose1Lwith1Ldisease
Mortality1LRate1L-1LANS--
Number1Lof1Ldeaths1Lwithin1La1Lpopulation1Lover1La1Lperiod1Lof1Ltime.1LUsually1Lgiven1Li
n1Ldeaths1Lper1L1,0001Lper1Lyear.