biostatistics notes for pg

8/17/2019 Biostatistics Notes for Pg

1/10


2/10

(qualit)SE=√(PQ/n)

(quant)95%CI=mean±2.5SE

(qualit)95%CI=proportion±2.5SE

(quant)sample size=Z²SE²/L²

(qualit)sample size=Z²PQ/L²

Z²=4, P=prevalence, Q=1–P, L=100-CI

probability

p(event)=n(experiment)/n(total event)

odds=n(event occur)/n(event not occur)

Poisson distribution-discrete probability distribution for random event

+ve/rt skew

mean>median>mode

–ve/lt skew

mean


3/10

p value 0.01-difference 99%signif

↑→ ↓CI level of signif

type I error-false +ve

type II error-false –ve

epidemiologic hypothesis specify population, expected outcome, sp cause, dose response relationship, time response

relationship

epidemiological study

cohort(AIR)-Attributable risk, Incidence, Relative risk-natural h/o ds, Hawthorn

effect-behaviour change when being observed

case control-Odds ratio

cross sectional-prevalence

ecological(best)-group characteristics-unit-population

observational study

descriptive

analytical

ecological-correlation-polpulation

cross sectional-prevalence-individual

case control-case reference-individual

cohort-follow up-individual

prospective-Framingham heart study, Doll&Hills study on smoking&ca lung

nested case control study

retrospective-effect of fetal monitoring on neonatal death, PVC exposure&

angiosarcoma liver COmbine-COurt Brown&Doll study on radiation therapy

experimental study

randomised control trial-clinical trial-pt

field trial-healthy people, introduce vacc for 1y old&see its efficacy

community trial-community intervention study-community

randomised control trial-dropout not excluded fr study

accuracy to test association b/n risk factor&ds systematic review& metaanalysis>

randomised control trial>

retrospective cohort>

prospective cohort>

case cohort>

cross sectional>


4/10

ecological

yield=new case d/t screening

→screen time=time(1st possible Dx final critical Dx)

→lead time=time(1st possibl Dx usual time Dx)

→serial interval=time(prim case sec case)→generation time=time(receipt of inf by host max infectivity)

T interval=no. of d bed of hosp remain vacant

incubat period≈generation time

RR/risk ratio=incid(exposed)/incid(non exposed)

AR=[incid(exposed)–incid(non exposed)]/incid(expos)

popul AR=[incid(population)–incid(not exposed)]/incid(population)

type of bias-technique

selection-randomisation surveillance/detection

Neyman survival/incidence prevalence

referral/volunteer

response

Berkesonian(hosp admission)

recall(memory)

bias d/t confounding-matching, multivariate analysis

information-single blinding

interviewer/observer-double blinding

statician-triple blinding

sensitivity=(true+ve/all ds)×100

specificity=(true–ve/all not ds)×100

+ve predictive value=(true+ve/all+ve)×100

–ve predictive value=(true–ve/all–ve)×100

diagnostic test-predictive value

false+ve%=(FP/total not ds)×100=1–sPecificity

false–ve%=(FN/total ds)×100=1–seNsitivity

efficiency(accuracy)=all true/all pt

likelihood ratio for +ve test=sensitivity/(1–specificity)

likelihood ratio –ve test=(1–sensitivity)/specificity pretest probability=prevalence+clinical assessm

posttest probability=pretest probability×likelihood ratio

↑ ↑ ↓sensitivity- TP- PPV

↑ ↑ ↓specificity- TN- NPV

sensitivity,specificity-criterion validity


5/10

multiple Dx test

↓ ↑ ↑series- sensitivity, specificity, PPV

↑ ↓ ↑parallel- sensitivity, specificity, NPV

best test to compare new&old test-Bland&Altman analysis

sampling

random/probability/nonpurposive-chance of being selected-same&known

simple

systematic

stratified(heterogenous)

multistage

Cluster(homogenous-Cost effective)

nonrandom/nonprobability/purposive

convenient quota/targetted

snowball/network

judgement

PQLI=IMR+life expectancy at age 1y+literacy rate, range=0-100, India=65(rank-63)

measure social, economic, politic policies

does not measure economic growth

HDI=GNI per capita+ life expectancy at birth+ (mean y of school, expected y of

school), range0-1, India=0.545(rank-136)

top-Norway, Australia, USA

bottom-Congo, Nigeria human poverty index1=long&healthy life(probability at birth not surviving 40y)+

knowledge(adult literacy rate)+ std of living(%of populat using improved H2O source+

%child underwt for age), India=31.3%

DALY(Disability Adjusted Life Y)=y of life lost+y lost to disability

burden of ds in populat

effectiveness of intervention

DFLE(Disability Free Life Expectancy)/active life expectancy=no. of y expected free of

disability if current pattern of mortality& disability continue to apply

HALE(Health Adjusted Life Expectancy)=life expectancy–time spent in poor health

QALY(Quality Adjusted Life Y)=no. of y added to life by intervention

type of data(NOIR)


6/10

Nominal(mode)-mal/fem, black/white, rural/urban

Ordinal(median)-1st,2nd, very satisfied,satisfied,dissatisfied

Interval(mean)-90°C,100°C,110°C

Ratio(mean)-pulse rate 90,100,110/min

correlation graph-scatter plot(correlation diagram)

+ve-change in same direction

–ve-change in opposite direction

r(Piersen correlation coefficient)

r=+1-perfect +ve

r=–1-perfect –ve

r=0-no correlation

–1≤r≤+1

r²=coeff of determination

0≤r²≤1 r2group

ANOVA(F) test

qualitative/categorical

Pearson chi² test/Fisher exact test/Yate correction

obesity

BMI(Quetlet index)=wt(kg)/ht(m²)

Brocca index-ideal wt(kg)=ht(cm)–100

corpulence index-actual wt/desirable wt≤1.2

Lorentz formula-ideal wt(kg)= ht(cm)–100–[{ht(cm)–150}/2(fem),4(mal)}]

skinfold thickn(MC meth)


7/10

midtriceps(best)+biceps+subscapular+suprailiac ≥50mm(fem),≥40mm(mal)

midtriceps≥18mm(mal), ≥32mm(fem)

waist circumf(cm)

World≥102(mal), ≥88(fem)

India≥90(mal), ≥80(fem)

waist/hip ratio>1.0(mal), >0.85(fem) waist/ht ratio(best CVS ds risk)≥0.5

contracept effectiveness

Pearl index

potency of contraception=(total accident preg/no. of pt observed×mth of use)×1200

life table analysis-best

prot quality assessm

digestibilty coefficient=(N2 absorbed/N2 intake)×100

biological value=(N2 retained/N2 absorbed)×100 net protein utilization=(N2 retained/N2 intake)×100=(biological value×digestibility

coefficient)/100

protein efficiency ratio=wt gain(g)/prot intake(g)

AA(chemical) score=[{(no. of AA/g prot)}/{(no. of same AA/g egg prot)}]×100

prot quantity assessm

prot energy ratio=(energy fr prot/total energy fr diet)×100

1g prot=6.25g N2

norm NPU=50-80

relative humidity=H2O vapour content/H2O vapour capacity

Box Whisker plot

quartile

forest plot

represent result in systematic review& metaanalysis(best study design)

funnel plot

assess publication bias

Kaplan Meier curve/product limit estimation survival fn fr lifetime data-#pt living for certain time after Rx

X-time, Y-%of survival

cox-proportion hazard model to control confounding factor in survival analysis

Levy Jenning chart

accuracy, quality monitoring


8/10

rate-numerator part of denominator, time is taken

IMR, incidence

ratio-numerator not part of denominator

std mortality rate, risk ratio, sex ratio, dependency ratio, coefficient of variance,abortion ratio

PRoportion-%

case fatality rate, PRevalence

abortion ratio=no. of abortion performed/no. of live birth

age sp death rate=(death age grp/MYP of same age grp)×1000

case fatality rate(CFR)=(death d/t ds/total case)×100

child sex ratio=no. of fem(0-6y)/no. of mal(0-6y)

child survival rate=(1000–under5 mortality rate)/10 crude birth rate=(8×TFR)+1

crude death rate=(no. of death during 1y/MYP)×1000

dependency ratio=[(0-14y+>65y)/(15- 65y)]×100

general fertilty rate=(no. of child born/reproductive women)×1000

gross reprod/fertility rate=no. of girl born/reproduct fem(no mortality)

incidence rate(I)=(no. of new case during a period/population at risk)×1000

maternal mortality RATE=(maternal death/reprod women)×1000

maternal mortality RATIO=(mat death/live birth)×1lac

net reproduct rate=no. of girl born/reproductive women(fix age sp fertility& mortality)

1-4y mortality(child death) rate=(death 1-4y/total childr1-4y)×1000

prevalenc ratio(P)=(total no. of all case/population at risk) P=I×duration of ds(time)

proportional mortality rate=(death d/t ds/total death)×100

sp death rate d/t caus=(no. of death d/t cause/MYP)×1000

standardised mortality ratio=(observed death/expected death)×100

survival rate=1–CFR

total fertilty rate=no. of child born/reproductive women(fix age sp fertility rate)

under5(child) mortality rate=(deathIMR

malaria

Annual Parasite Incidence(API)

=(confirm case in 1y/populat)×1000

Annual Bld Examinat Rate(ABER)


9/10


10/10

HAS BEEN TAKEN FROM VARIOUS STANDARD TEXTBOOKS. FOR ANY

FEEDBACK/QUERY PLEASE CONTACT- [email protected] or

[email protected] )

biostatistics notes for pg

Documents