NRl 503/l NR503l Midterml Exam:l
Populationl Health,l Epidemiology,l &l
Statisticall Principlesl Reviewl (Latestl 2026/l
2027l Update)l |l Qsl &l As|l Gradel A|l
100%l Correctl (Verifiedl Answers)-l
Chamberlain
QUESTION
Thel Epidemiologicall Triangle
Answer:
Thel modell consistsl ofl threel interactivel factors:l
thel causativel agentl (thosel factorsl forl whichl presencel orl absencel causel disease—
biologic,l chemical,l physical,l nutritional),l
al susceptiblel hostl (thingsl suchl asl age,l gender,l race,l immunel status,l genetics),l andl
thel environmentl (includingl diversel elementsl suchl asl water,l food,l neighborhood,l
pollution)
QUESTION
Causall Relationships
Therel arel fourl typesl ofl causall relationships
Answer:
1.l Necessaryl andl sufficient:l Al factorl isl bothl necessaryl (i.e.,l diseasel willl occurl onlyl ifl
thel factorl isl present),l andl sufficientl (i.e.,l exposurel alwaysl leadsl tol disease).
2.l Necessaryl butl notl sufficient:l Morel thanl onel factorl isl required,l usuallyl inl al temporall
sequence.l Forl example,l whenl consideringl tuberculosis,l thel tuberclel bacillusl isl al
necessaryl factor,l butl evenl itsl presencel mayl notl bel sufficientl tol producel thel diseasel inl
everyl individual.
,QUESTION
Causall Relationships
Therel arel fourl typesl ofl causall relationships
Answer:
3.l Sufficientl butl notl necessary:l Al specificl factorl canl causel al diseasel process,l butl otherl
factorsl byl themselvesl canl causel thel samel disease.l Forl example,l vitaminl B12l deficiencyl
canl causel anemia,l butl otherl factorsl canl resultl inl anemial asl well.
QUESTION
Causall Relationships
Therel arel fourl typesl ofl causall relationships
Answer:
4.l Neitherl sufficientl norl necessary:l Al specificl factorl canl bel combinedl withl otherl
factorsl tol producel disease.l However,l thel diseasel mayl bel producedl evenl inl thel absencel
ofl thel factor.
Forl example,l multiplel riskl factorsl forl thel developmentl ofl heartl diseasel arel neitherl
sufficientl norl necessary.
QUESTION
Whatl doesl itl takel tol actuallyl establishl causation?l Thel followingl arel necessary.
Answer:
1.l Temporall relationship:l Thel associatedl factorl mustl bel presentl beforel thel disease.
2.l Strengthl ofl association:l Thisl isl thel oddsl ratiol orl relativel risk.l Thel higherl orl
strongerl thel relationship,l thel morel likelyl itl isl causal.
3.l Dose-responsel relationship:l Asl thel dosel increases,l sol doesl thel riskl ofl developmentl
ofl thel disease.
4.l Replicationl ofl findings:l Thel findingsl canl bel foundl inl repeatedl study.
QUESTION
Whatl doesl itl takel tol actuallyl establishl causation?l Thel followingl arel necessary.
Answer:
5.l Biologicall plausibility:l Currentl knowledgel onl thel factorl orl exposurel andl thel responsel
ofl thel humanl bodyl onl al cellularl levell isl consistentl withl thel findings.
6.l Alternatel explanationsl arel considered.
, Riskl ofl thel diseasel decreasesl withl cessationl ofl exposure.
l Thel findingsl arel consistentl withl otherl knowledge.
l Thel associationl isl specific:l Al specificl exposurel isl associatedl onlyl withl onel disease.
QUESTION
Whenl al researcherl drawsl thel wrongl conclusionl becausel ofl al probleml withl thel researchl
methodologyl whatl isl thel result?
Answer:
Al typel 1l orl typel 2l errorl occurs
QUESTION
Differentiatel betweenl al
Typel 1l error
Typel 2l error
Answer:
Al typel Il errorl occursl whenl al nulll hypothesisl isl rejectedl whenl inl factl itl isl true.l
Concludel Relationshipl Existsl (Rejectl Nulll Hypothesis)l +l relationshipl doesl NOTl existl =l
Typel 1l error
Al typel IIl errorl occursl whenl onel failsl tol rejectl al nulll hypothesisl whenl inl factl itl isl
false.
Concludel Relationshipl Doesl Notl Existl (Faill tol Rejectl Nulll Hypothesis)l +l relationshipl
existsl =l Typel 2l error
QUESTION
Therel arel twol basicl formsl ofl errorl ofl measurement:
Answer:
randoml errorl (alsol knownl asl nondifferentiall error)l andl systematicl errorl (alsol knownl asl
bias)
QUESTION
Randoml errorsl occurl asl thel resultl ofl thel usual
Answer:
Populationl Health,l Epidemiology,l &l
Statisticall Principlesl Reviewl (Latestl 2026/l
2027l Update)l |l Qsl &l As|l Gradel A|l
100%l Correctl (Verifiedl Answers)-l
Chamberlain
QUESTION
Thel Epidemiologicall Triangle
Answer:
Thel modell consistsl ofl threel interactivel factors:l
thel causativel agentl (thosel factorsl forl whichl presencel orl absencel causel disease—
biologic,l chemical,l physical,l nutritional),l
al susceptiblel hostl (thingsl suchl asl age,l gender,l race,l immunel status,l genetics),l andl
thel environmentl (includingl diversel elementsl suchl asl water,l food,l neighborhood,l
pollution)
QUESTION
Causall Relationships
Therel arel fourl typesl ofl causall relationships
Answer:
1.l Necessaryl andl sufficient:l Al factorl isl bothl necessaryl (i.e.,l diseasel willl occurl onlyl ifl
thel factorl isl present),l andl sufficientl (i.e.,l exposurel alwaysl leadsl tol disease).
2.l Necessaryl butl notl sufficient:l Morel thanl onel factorl isl required,l usuallyl inl al temporall
sequence.l Forl example,l whenl consideringl tuberculosis,l thel tuberclel bacillusl isl al
necessaryl factor,l butl evenl itsl presencel mayl notl bel sufficientl tol producel thel diseasel inl
everyl individual.
,QUESTION
Causall Relationships
Therel arel fourl typesl ofl causall relationships
Answer:
3.l Sufficientl butl notl necessary:l Al specificl factorl canl causel al diseasel process,l butl otherl
factorsl byl themselvesl canl causel thel samel disease.l Forl example,l vitaminl B12l deficiencyl
canl causel anemia,l butl otherl factorsl canl resultl inl anemial asl well.
QUESTION
Causall Relationships
Therel arel fourl typesl ofl causall relationships
Answer:
4.l Neitherl sufficientl norl necessary:l Al specificl factorl canl bel combinedl withl otherl
factorsl tol producel disease.l However,l thel diseasel mayl bel producedl evenl inl thel absencel
ofl thel factor.
Forl example,l multiplel riskl factorsl forl thel developmentl ofl heartl diseasel arel neitherl
sufficientl norl necessary.
QUESTION
Whatl doesl itl takel tol actuallyl establishl causation?l Thel followingl arel necessary.
Answer:
1.l Temporall relationship:l Thel associatedl factorl mustl bel presentl beforel thel disease.
2.l Strengthl ofl association:l Thisl isl thel oddsl ratiol orl relativel risk.l Thel higherl orl
strongerl thel relationship,l thel morel likelyl itl isl causal.
3.l Dose-responsel relationship:l Asl thel dosel increases,l sol doesl thel riskl ofl developmentl
ofl thel disease.
4.l Replicationl ofl findings:l Thel findingsl canl bel foundl inl repeatedl study.
QUESTION
Whatl doesl itl takel tol actuallyl establishl causation?l Thel followingl arel necessary.
Answer:
5.l Biologicall plausibility:l Currentl knowledgel onl thel factorl orl exposurel andl thel responsel
ofl thel humanl bodyl onl al cellularl levell isl consistentl withl thel findings.
6.l Alternatel explanationsl arel considered.
, Riskl ofl thel diseasel decreasesl withl cessationl ofl exposure.
l Thel findingsl arel consistentl withl otherl knowledge.
l Thel associationl isl specific:l Al specificl exposurel isl associatedl onlyl withl onel disease.
QUESTION
Whenl al researcherl drawsl thel wrongl conclusionl becausel ofl al probleml withl thel researchl
methodologyl whatl isl thel result?
Answer:
Al typel 1l orl typel 2l errorl occurs
QUESTION
Differentiatel betweenl al
Typel 1l error
Typel 2l error
Answer:
Al typel Il errorl occursl whenl al nulll hypothesisl isl rejectedl whenl inl factl itl isl true.l
Concludel Relationshipl Existsl (Rejectl Nulll Hypothesis)l +l relationshipl doesl NOTl existl =l
Typel 1l error
Al typel IIl errorl occursl whenl onel failsl tol rejectl al nulll hypothesisl whenl inl factl itl isl
false.
Concludel Relationshipl Doesl Notl Existl (Faill tol Rejectl Nulll Hypothesis)l +l relationshipl
existsl =l Typel 2l error
QUESTION
Therel arel twol basicl formsl ofl errorl ofl measurement:
Answer:
randoml errorl (alsol knownl asl nondifferentiall error)l andl systematicl errorl (alsol knownl asl
bias)
QUESTION
Randoml errorsl occurl asl thel resultl ofl thel usual
Answer:
