Biostats Qu Collection

7/28/2019 Biostats Qu Collection

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which one of the following can be used for data analysis in Cross sectional?1. Odds ratio2. Relative risk3. Chi square test ***4. Attributable risk and Chi square test

5. odds ratio and attributable riskcross sectional: use CHI SQUARECohort: use RR or ARCase control: use ODD's RATIO

Which is the best study to find out the state of Vitamin D deficiency in Australia?a..cohort

b..case controlc..case studyd..Cross-sectional study.***

For Prevalance Cross Sectional Study ..... to check incidence Cohort .... So D here

Two groups are being studied for risk reduction for some disease with aspirin use. Tables are given asfollows.

Aspirin used aspirin not usedGot disease 10 20Disease free 990 980Calculate NNT for this?a. 10

b. 100 ***c. 1000

its incidance 10 among 1000 population right so inverse of it is 1000/10=100\

The question says 10 got disease amongst 1000 people who used aspirin and 20 amongst

those who did not use it so take the total number which is 1000/ 10 = 100 is ur ans.

In a village of 3000 people, 500 get Congo Hemorrhagic fever. 450 eventually recover fromthe disease in the next 4 weeks while 50 died. What is the case fatility rate for this disease?1. 10 ***2. 203. 354. 505. 200


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Case fatality rate = # of deaths from a specific cause / total number of cases with same disease...

50 / 500 = 10 (A)

You are a doctor in a town ,where 6people out of 100 are non smoker.What are thechances of stroke.the chances of stroke in smoker is 50%more than non smoker .Nowthe pharmaceutical company is introducing a medicine which reduces the chances ofstroke upto 1/3rd in smoker population .What is the percentage of the stroke populationwill get strokea)3%b)6% ***c)9%

d)12%e)20%

6/100 = 6%, 6*1.5 = 9 , 1/3rd reduced so 9/3 = 3, => 9-3 = 6%

9/3 is to calculate reduction which is 1/3 so 9/3. Final level is if yousubstract the 1/3 reduction from the 50% increased incidence that will give you final incidence orprevalence whatever is asked in the stem.

just take it as in general population this risk is 6/100 ... for smokers it turns to be 9/100 as gnrlpopulation has 50% less thn smokers... so in smokers risk is reduced to one third ... so we ll take1/3rd of 9 which ll be 3 nd subtarct it from orignal risk of 9 in smokers nd v ll be left wid 6

In a small village of North QLD with a community of 3000 people, 18%females getURTI while 22% males get it as well who are exposed to factory smoke. 10% offemales also get URTI who live away from the factory and are not exposed to

factory smoke. The data for males is not available. Calculate the attributable risk forfemales to get URTI due to factory smoke?1. 28%2. 30%3. 6%4. 1.8%5. 8% ***

ARR =risk in exposed Group - risk in Unexposed group So 18 - 10 = 8%


3/23

A study wish to make a relation btw the fatigue in track car driver in high ways & theincidence of MVA happen. wt is the most suitable method to carry out study?a, cohortb, case control ***c, RCT

D,cross sectionalE,case study

least imp study to look for effectiveness of ccf Rx?a,case controlb, case series ***c, cohortd,RCTe, Systemic Review

What is the best method of study for studying the relation between fatigue andaccident in truck driver?

a. RCTb. Cohort

c. A retrospective case-control study ***d. Case reporte. systemic review

You find there are more and more diabetics in your practice and you want to do a

research abouthow many people are diabetic. What is the best study design?a. Cohort studyb. Case-control studyc. Randomized-control triald. Cross-section study ***


4/23

If you need to study whether smoking causes myocardial infarction, what kind ofstudy / group do you intend to conduct/study?

A) Cohort ***B) Randomized Controlled

C) Case ControlD) Case seriesE) Observational

least imp study to look for effectiveness of ccf Rx?a,case controlb, case series ***

c, cohortd,RCTe, Systemic Review

A study wish to make a relation btw the fatigue in track car driver in high ways &the incidence of MVA happen. wt is the most suitable method to carry out study?a, cohortb, case control ***

c, RCTD,cross sectionalE,case study

A young scientist has decided to study the causes of neonatal jaundice. He selects 150 babys withjaundice and 150 without, and examines there previous historiies looking for factors that could havedetermined there jaundice. This kind of study is called?a.) cohort studyb.) case studyc.) case control study ***d.) prospective study

in case control you choose a group with the disease, and then you choose a control groupwithout the disease and then you follow them retrospectively

C


5/23

A scientist study a case which is 30% fpv, 10% fnv.study of 1100.now the test shows 100people are +ve for the test.what is the actual number of people getting the disease for thepeople who did testing?a, 10b, 20

c, 30d, 70 ***e,90

here we say that 100 are positve for the test (TP+FP). of these 100 30% are FPV which meansthat TP (70) and FP (30). Then we have remaining 1000 of which 10% are FN, this comes out as100. Then lastly we have T- (900). So the 2x2 table is TP (70) FP (30) F- (100) T- (900). Now wewant to know the positive predictive value (likelihood that a positive result in test indicatesdisease). Formula is (TP/(TP+FP)). so (70)/(70+30)=70%

You want to make a study about asthmatic patients and if there have been anyexposure to smoke orits severity to exposure to smoke. What study is the most appropriate?a. Case control ***b. Cross sectionalc. Cohortd. Observational study

A study is being planned to investigate the effect of environmental exposure to pesticides on

the incidence of cancer.

Which of the following study designs is most appropriate?

1.Case-control study

2.Case series

3.Cohort study ***

4.Cross-sectional survey

5.Randomised controlled trial


6/23

The cut off point of screening test is increased.A. both sen and sp will increasedB Sen increased, Sp decreasedC.Sen decreased, SP increased***

Australian government appointed you to go through a community based service and help alocal doctor there.Hepatits B data given in a community of total population of 200.

2009 2010Antibody +ve cases 10 15Antigen +ve cases 40 55

Need to calculate the prevalence per 1000 population in the year 2010A- 350 ***B- 250C- 70D- 50E- 125

for 2010 its 15 + 55 = 70 / 200* 1000 = 350

for 2009 its 40 + 10 = 50 / 200 * 1000 = 250

Which study is most reliable for outcome of a disease in a community?A-cohort

B-case controlC-RCT ***D- case studyE- cross sectional study


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A post marketing drug surveillance study of a new heart failure therapy to the market was

carried out on 10,000 subjects who had completed clinical trials. which one of the followingmost accurately reflects the information genereated from such a study?1. Adverse events profile ***2. comparative therapeutics efficacy3. cost benefits trial4. cost effectiveness5. Drug potency

A new screening test is to be launched in community. Which is the most importantfactor to consider?A. High sensitivity *** not confirmed yetB. High specificityC. High positive predictive valueD. No adverse outcomes

for screening test high sensitivity and for confirmatory high specificity

Good screening tests have high sensitivity,

pecificty-confirmatory.

Which report provides the least information ?A) Case controlB) Cohort studyC) RCTD) Case report ***

What study would you do if you want to find out the efficacy of a vaccineon a group of people?a) Randomised controlled trials ***b) Cohort studyc) Case control studyd) Cross sectional study


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Ten day care clinic patients have their Hb measured in the clinic. The means Hb value is11.0. The first 9 values are 10.0, 10.2, 9.7, 13.4, 12.7, 12.1, 11.0, 12.8, 8.6.what is the value of the 10th patient?A. 8.5B. 9.0

C. 9.5***10. 10.0E. 10.5

In a trial of a new treatment for fulminant sepsis the mortality in the treatment group is

20%, whereas the mortality in the placebo group is 40%. What is the relative risk of deathwith the new treatment?A. 0.1B. 0.2C. 0.4D. 0.5 ***E. 2.0

incidence exposed/incidence non exposed = 20/40 = 0.5...D

A new screening test was developed for a disease. According to the survey, there is anincrease in percentage of people who are taking the screening test. However, there is noincrease in number of people diagnosed with the disease. Whats the underlying cause?A. Because of the cultural limitation, the number of Indigenous women who take the testare few.B. There is not enough access to the test for the communityC. The test has low sensitivity value***

A new drug was launched in the market after getting over with the non-inferiority trials. Thedrug,s P value at the end of the trial was


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A new drug is discovered, which affects the progression of the disease, but not themortality. Which is the most appropriate statement?.a. increase incidenceb. decrease incidencec. Increase prevalence ***

d. decrease prevalence

A pharmaceutical company before the start of the trial got approval from ethical committeeto use a new anti-cancer drug for ca.Pancreas. The ethical committee gave approval and setthe target P value< or = 0.02, for the drug to be superior to other drugs. At the end of thetrial, the company claimed about the efficacy of the new drug to be superior to all otheravailable drugs in the market and P value at the end of the trial was = 0.04. What does thisP value show here.

1. New drug is safer as compared to other drugs.

2. New drug is as useful as other drugs with fewer side effects

3. new drug is superior to other drugs

4. New drugs is not to superior to other drugs

5. New drug is inferior to other drugs

if a p value is less than 0.05 then diffe is significant , But here they changed the standardand set it at 0.02 instead of 0.05... Here you just forget about this 0.05. Now compare

0.02 and 0.04 and conclude your result from this!!... if i had not given you 0.02 as theacceptable P value for this trial then it was 0.05 but now i have given you a standard Pvalue so why you bather about 0.05 then anymore... 0.04> 0.02 so it means drug is notsuperior to other drugs.. For superiority of the drug, it should have been trial final P value< Standard P value. Which is not the case here.... Here only two things should confuseyou, Drug is inferior to other drugs and drug is superior to other drugs. Here they can askyou that drug isinferior, so your justification for rejecting this is that as the trial was for superiority, so wecan only comment on its superiority status here, not inferiority status

P value less thn 0.01 means something is highly specific, i.e there's only 1% chanceof occurrence of an observed difference. The standard p value is 0.05 which meansthat theres 5% chance of difference to occur. If p value exceeds 0.05 in a research,

the test hypothesis is nullified.

In pt. with pancreatitis for purpose of statistical studies ,AOF are useful EXCEPT-a.Case controlb.Cohort

c.Case report/case study(one study) ***d. double blind studye.systemic review


10/23

WOF the following least describe primary prevention?A. reduce incidenceB. improve lifestyleC. giving vaccinationD. reduce prevalence

E.identify the predisposing factor early ***

heirrarchy of evidence , least explained in what

A.case control

B.case report ***

C.systemic review

D.cohort

E. randomised control

as a gp in rural area, you notice that recently more cases of hepatitis c has beendiagnosed and want to do a research to find out the incidence of hep c in the communitywith a population of around 3000. how will you get the information you need for theresearch?a. find the number of all patients with current hepatitis c antibody +b. all patients with current hepatitis c antigen positive

c. all patients with current hepatitis c pcr positive ***c. all cases diagnosed as hepatitis c positive for the past 5 years

You are a doctor in a hospital and want to do research about the outcome of babies

born to diabetic mothers and want to compare the result with the babies born to nondiabetic mothers.Which study will be the best study?a) Cross sectional studyb) Cohort studyc) Case control study ***d) Randomized control triale) Case study


11/23

You find there are more and more diabetics in your practice and you want to do a researchabouthow many people are diabetic. What is the best study design?a. Cohort studyb. Case-control study

c. Randomized-control triald. Cross-section study***

Which of the following is necessary in obtaining informed consent?a. A description of the statistical analyses that will be carried outb. A description of the purpose of the research ***c. A description of the reliability and validity of test instruments

d. A list of publications that the researcher has had in the last ten years

You are supposed to submit a paper or protocol of what will be done in the researchstudy and how it will be done to an ethical committee and on the basis of that, Ethicalcommittee either approves it or rejects it.

How to choose sample for a research of obesity in the community?

A. Snowballing

B. From shopping center.

C. Random in general population.***

D. From news advertisement.

E. From website

You are planning on conducting a research to look at the association between hypertensionand myocardial infacrtion. What is the most appropriate study design for thisresearch?a. Randomised controlled trialb. Case studyc. Cohort ***

d. Cross sectional


12/23

if there is experimental study then we will choose RCT.. but if there is observationalstudy look that is there any comparison grp..if yes it means we go for analytic study...Cohort study(exposure to outcome) outcome to exposure(case control) and exposue andoutcome at same time then cross sectional....there is hypertension is exposure and MI isoutcome..so we will go for cohort study

15 year old boy wants to participate in a research study. He told his parents who didnot agree. He lives with his parents. Can this boy participate in the research study?

No,Minor living with parents..Ethics would need parents consent

What is the advantage of a randomised controlled trial?

A)will remove observer bias ***

b)will remove the chance of self selection of patients to particular group

c)will be better for comparable resultsThe most important advantage of proper randomization is that it minimizes allocationbias, balancing both known and unknown prognostic factors, in the assignment oftreatments

When evaluating a report of clinical trial, which one of the following is correct?

A. Control and treatment groups must be equivalent in size.

B. if randomization is conducted properly, chance differences are inevitable.***

C. Inadequate sample size has been shown to produce true positives and true negatives.

D. results are invalid if the trial is of not double blind construction.

E. Withdrawal of patients from a trial by the investigator does not lead to bias


13/23

Which of the folowing statement about double blind pacebo control clinical trial is correct!A: All patients receive a placebo.B: Everybody receives both treatmentsC. Some of the patients are not treatedD. Half of the patients don,t know which treatment they receive

E. The clinician assessing the effects of the treatment does not know which treatment thepatient has been given***

Incidence rate of lung cancer among smokers is 10/1000 and among non smokers is 1 per

1000.The extent to which lung cancer can be attributed to smoking is-

a. 10%b. 90% ***

c.1%

d. 100%

ic exposed-inc non exposed / inc exposed

In a community pap screening was done. but there is increased incidence of Ca cervix.what is the cause?failure to screen the high risk womeninability of the test to identify the disease in early stage.***

What would be the best reason to make a screening program more available to thepublic?a) Possibility of early diagnosisb) It is required for research purposesc) It improves the treatments prognosisd) Specialised treatment is availablee) It can lower the death rate from the disease***


14/23

the disease should be common, treatable and easy screend with cheapavaliable non-invasive screeing procedure

Average BP is 130 +/- 25. about 95% people will lie between :a. 115-155b. 80-180***c. 95-100

for 100% its +/-D, for 95% its +/-2D

for 50% it is +/- 3SD

130 IS MEAN AND 25 IS 2 SD, 95 WILL FALL WITH 2 SD so 25=2 SD=50,......... 50+130=180 130-50=80 then its 80 180

one population , mean systolic BP is 115 and SD is 15 so what will be rangeof 95% populations BP?a) 100 to 130

b) 85 to 145***

95% SD(range) given then it means its plus and minus 2SD.so here they havegiven 15 SD,SO As i said its 2SD for 95% and 2*15=30 so plus and minus 30

if they give 99% then its plus and minus 3SD

if 66% then plus and minus 1SD

on tv u have given a lecture . u gave education, now we need to find out that is itbenefitting the people or not.

a go for randomized group in general population.***B case study

C case controlD cohart


15/23

A pharmaceutical company contacts you and suggests you to start prescribing the newantidepressant. What the criteria for doing that?A. Approval of committee ethics commission ***B. Base recent scientific researchC, Not to do so

50 male taken to a research and during it he become dementia and his primary carier is hisson what will you doa) Ask from son***b) Gardianship

c) Ethic and comity

You are planning on conducting a research to look at the association between hypertensionand myocardial infacrtion. What is the most appropriate study design for this research?a. Randomised controlled trialb. Case studyc. Cohortd. Cross sectional

Well not sure, whether they are asking here about all participants beinghypertensive or one group is Hypertensive and another not hyptertensive, if thatis the case then its C But if all participants are hypertensive, then A is the betterone.

If you need to study whether smoking causes myocardial infarction, what kind of study /group do you intend to conduct/study?

A) Cohort ***B) Randomized ControlledC) Case ControlD) Case seriesE) Observational


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1. Adverse events profile***

2. comparative therapeutics efficacy

3. cost benefits trial

4. cost effectiveness

5. Drug potency

because always we look for drug which has less averse effects, Post marketing

studies are basically placed in Phase 4 studies and in these kind of studies, people

from extreme ages are taken to see even the rarest possible adv. event which can

happen.These are mostly done after approval of the drug for the market which is

phase 3 study mostly

7) An experienced group of surgeons report on a randomised placebo

controlloed trial comparing a particular surgical technique for carotid artery to

a sham procedure. Their study concludes that using this advanced method

reduces the risk of stroke from 5% to 4% ( p


18/23

Calculate the attributable risk for females to get URTI due to factory smoke?

1. 28%

2. 30%

3. 6%

4. 1.8%5. 8%

11)A pharmaceutical company before the start of the trial got approval from

ethical committee to use a new anti-cancer drug for ca.Pancreas. The ethical

committee gave approval and set the target P value< or = 0.02, for the drug

to be superior to other drugs. At the end of the trial, the company claimed

about the efficacy of the new drug to be superior to all other available drugs

in the market and P value at the end of the trial was = 0.04. What does this P

value show here.

1. New drug is safer as compared to other drugs.2. New drug is as useful as other drugs with fewer side effects

3. new drug is superior to other drugs

4. New drugs is not to superior to other drugs

5. New drug is inferior to other drugs

Explanation: if a p value is less than 0.05 then diffe is significant , But here they

changed the standard and set it at 0.02 instead of 0.05... Here you just forget

about this 0.05. Now compare 0.02 and 0.04 and conclude your result from this!!...

if i had not given you 0.02 as the acceptable P value for this trial then it was 0.05

but now i have given you a standard P value so why you bather about 0.05 then

anymore... 0.04> 0.02 so it means drug is not superior to other drugs.. For

superiority of the drug, it should have been trial final P value < Standard P value.

Which is not the case here.... Here only two things should confuse you, Drug is

inferior to other drugs and drug is superior to other drugs. Here they can ask you

that drug is inferior, so your justification for rejecting this is that as the trial was

for superiority, so we can only comment on its superiority status here, not

inferiority statu

12)Which is the best study to find out the state of Vitamin D deficiency in Australia?

a) cohort

b) case controlc)case study

d) Cross-sectional study ***

... For Prevalance Cross Sectional Study, To check incidence Cohort .... So D here

13) on tv u have given a lecture . u gave education, now we need to find out that is it benefitting the

people or not.a go for randomized group in general population.B case study

C case controlD cohart


19/23

14) You are a doctor in a town ,where 6people out of 100 are non smoker.What are the chances ofstroke.the chances of stroke in smoker is 50%more than non smoker .Now the pharmaceuticalcompany is introducing a medicine which reduces the chances of stroke upto 1/3rd in smokerpopulation .What is the percentage of the stroke population will get stroke

a)3%b)6% ****c)9%d)12%e)20%

Ans:B....6/100*100= 6%

15) A study is being planned to investigate the effect of environmental exposure to

pesticides on the incidence of cancer.

Which of the following study designs is most appropriate?

1.Case-control study

2.Case series

3.Cohort study

4.Cross-sectional survey

5.Randomised controlled trial

some imp epidemiology formulas and related imp notes...that might be helpful for

exm..

TP- true positive

TN - treu negatives

FP- false positive

FN - false negatives

accordingly formulas r as follows :

1.) SENSITIVITY = TP/ TP+ FN


20/23

2.) SPECIFICITY = TN/TN+ FP

3.) PPV - POSITIVE PREDICTIVE VALUE = TP/TP+FP

4.) NPV- NEGATIVE PREDICTIVE VALUE = TN/TN+FN

5.) FN RATE = 1 - SENSITIVITY

6.) FP RATE = 1 - SPECIFICITY

7.)Accuracy(efficiency) of test = ability to give correct result = TP+TN/ TP+TN+FP+FN

8.) FP % = FP/Total not diseased * 100

9.) FN % = FN/ Total diseased * 100

10.) Likelihood ratio of a positive Test- LR+ = TP/ Tot diseased /// FP/tot not diseased( /// means

whole upon)

11.)Likelihood ratio of a negative Test- LR- = FN/ Tot diseased /// TN/tot not diseased( /// means

whole upon)

12.) LR + = sensitivity/ 1-specificity

13.) LR - = 1- sensitivity/ specificity

(just a small explnation for Likelihd ratio wat it means.

e.g If LR+ =9 for a test say ELISA, then it means that likelihood of ELISA test to be

positive in HIV patients is 9 times more than not having HIV.. )


21/23

dis+ dis-

test + a(TP) b(FP)

test - c(FN) d(TN)

these formulas u can easily remember with help of above small table. try making

arrows in your rough notes. like for sensitivity = a/a+c so arrow is downwards..thats

how i remembered...i hope u understood...anyways...

SOME IMP formulas TO REVISE

1.) Case Fatality Rate = no. of deaths(disease)/ tot no of cases(diseases) * 100

2.) INCIDENCE = new cases

3.) PREVALENCE = old + new cases

4.) Prevalence = Incidence * Duration (mnemonic = PID : P=I*D)

5.)ODDS RATIO = ad/bc

( see the above table , its simply the cross product, try drawing an arrow again , it vl

give u a cross...)

6.)COHORT study is = Prospective/ forward/ longitudinal study where we go from

Cause to Effect

e.g Risk factor to disease...meaning we study all smokers(RISK FACTR) and

then follow them up for Lung Cancer(DISEASE)


22/23

7.) CASE CONTROL STUDY = backward/ retrospective study

Here we study the diseased people and look for their risk factor.

e.g We stdy all Females with cervical cancer(clear cell ca) and then look for being

exposed to DES( diethyl stilbesterol..) i hope u all getting wat i m writing...;)

8.)RELATIVE RISK(RR) = INCIDENCE among Exposed/ INCIDENCE among Non-

Exposed

if RR 1 : association+(i.e association of disease with Risk factr)

9.)ARR-attributalbe risk = Risk in exposed Group - risk in Unexposed

but i read somewhere that : Risk in exposed Group - risk in

Unexposed///risk(exposed)

guys please confirm it...!! Drzahid khan i rem u said first formula...:)

10.)mean +/- 1SD = 68% CI

mean +/- 2SD = 95% CI

mean +/- 3SD = 99% CI

SD - standard deviation

CI - confidence interval


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