Biostatistics MCQ (AIIMS)
A physician, after examining a group of patients of a certain disease, classifies the condition of each one as ‘Normal’, ‘Mild’, ‘Moderate’ or ‘Severe’. Which one of the following is the scale of measurement that is being adopted for classification of the disease condition?
[AIIMS Nov 92 Dec 98, May 94]
(a) Normal
(b) Interval
(c) Ratio
(d) Ordinal
there is an intrinsic order in ordinal data set. e.g. Mild, Moderate, Severe
In the WHO recommended EPI cluster sampling for assessing primary immunization coverage, the age group of children to be surveyed is
(a) 0-12 months [AIIMS Nov1992, & 2008]
(b) 6-12 months
(c) 9-12 months
(d) 12-23 months
children aged 12–23 months, if the final primary vaccination is at 9 months of age – this is the most commonly chosen target population (Ref: WHO EPI cluster sampling)
If a biochemical test gives the same reading for a sample on repeated testing, it is inferred that the measurement is [AIIMS June 1992]
(a) Precise
(b) Accurate
(c) Specific
(d) Sensitive
Precision means repeatability
Mean, Median and Mode are [AIIMS Dec 94, & Nov 2007]
(a) Measures of dispersion
(b) Measures association between two variables
(c) Test of significance
(d) Measures of central tendency
Following are the sampling techniques used to conduct community health surveys, except
(a) Simple random [AIIMS May 1994]
(b) Systematic random
(c) Stratified random
(d) Cluster testing
Median weight of 100 children was 12 kgs. The standard deviation was 3. Calculate the percent coefficient of variance [AIIMS May 1994]
(a) 25%
(b) 35%
(c) 45%
(d) 55%
In statistical literature data are broadly classified as interval scale data, ordinal scale data & categorical data. Blood groups will be an example for: [AIIMS Dec 1994]
(a) Interval scale data
(b) Ordinal scale data
(c) Categorical data
(d) None of the above
Chance of passing a Genetic disease “y” trait by the affected parents to children is 0.16. They plan to have two children. Probability of both the children having “y” trait is [AIIMS Dec 1994]
(a) Zero
(b) 0.16
(c) 0.32
(d) 0.0256
A population study showed a mean glucose of 86 mg/ dL. In a sample of 100 showing normal curve distribution, what percentage of people have glucose above 86mg/ dL [AIIMS Dec 94]
(a) 34
(b) 50
(c) NIL
(d) 68
How much of the sample is included in 1.95 SD? [AIIMS May 1995]
(a) 99%
(b) 95%
(c) 68%
(d) 65%
(a) 34
(b) 50
(c) NIL
(d) 68
How much of the sample is included in 1.95 SD? [AIIMS May 1995]
(a) 99%
(b) 95%
(c) 68%
(d) 65%
Square root of p1q1/n1 + p2q2/n2 is a measure of [AIIMS Dec 1995]
(a) Mean
(b) Standard error of difference between two means
(c) Standard error of difference between two proportions
(d) Normal deviate
Histogram is used to describe: [AIIMS Dec 1995]
(a) Quantitative data of a group of patients
(b) Qualitative data of a group of patients
(c) Data collected on nominal scale
(d) Data collected on ordinal scale
If 60 values are arranged in ascending order, middle value is [AIIMS Dec 1995]
(a) Arithmetic Mean
(b) Median
(c) 30th percentile
(d) 31st percentile
50th percentile is equivalent to [AIIMS Sep 1996]
(a) Mean
(b) Median
(c) Mode
(d) Range
A normal distribution curve depends on [AIIMS Feb 1997]
(a) Mean and sample size
(b) Range and sample size
(c) Mean and standard deviation
(d) Mean and median
In a drug trial A 50 yr old patient with CAD is being interviewed about his dietary & smoking habits. The possible bias that might be introduced might be: [AIIMS Feb 1997]
(a) Selection bias
(b) Berkesonian bias
(c) Recall bias
(d) No possibility of bias
The Correlation Coefficient between Smoking & Lung Cancer was found to be 1.4. This indicates
(a) Weak correlation [AIIMS Feb 1997]
(b) Moderate correlation
(c) Strong correlation
(d) Mistake in calculation
A Scatter diagram is drawn to study: [AIIMS June 1997]
(a) Trend of a variable over a period of time
(b) Frequency of occurrence of events
(c) Mean & median values of the given data
(d) Relationship between two given variables
Which of the following is not true about ‘correlation’? [AIIMS June 97]
(a) It indicates degree of association between two characteristics
(b) Correlation coefficient of 1 means that the two variables exhibit linear relationship
(c) Correlation can measure risk
(d) Causation implies correlation
If we know the value of one variable in an individual & wish to know the value of another variable, we calculate - [AIIMS June 1997]
(a) Coefficient of correlation
(b) Coefficient of regression
(c) SE of mean
(d) Geometric mean
A cardiologist wants to study the effect of an antihypertensive drug. He notes down the initial systolic blood pressure (mmHg) of 50 patients and then administers the drug on them. After a week’s treatment, he measures the following is the most appropriate statistical test of significance to test the statistical significance of the change in blood pressure
[AIIMS June 1997, AIIMS May 1995, AIIMS Nov 2004]
(a) Paired t-test
(b) Unpaired or independent t-test
(c) Analysis of variance
(d) Chi-square test
Not required for Chi-square test is [AIIMS Dec 1997]
(a) Mean & SD of the groups
(b) Each expected cell frequency > 5
(c) Large sample
(d) Contingency Table
The mean B.P. of a group of persons was determined and after an interventional trial, the mean BP was estimated again. The best test to be applied to determine the significance of intervention is
(a) Chi-square [AIIMS Dec 1997]
(b) Paired ‘t’ test
(c) Correlation coefficient
(d) t-test
Study finds a correlation coefficient of + 0.7 between self reported work satisfaction & expectancy of life in a random sample of 5000 corporate workers. (p = 0.01). This means that [AIIMS Dec 1997]
(a) Work satisfaction improves life expectancy
(b) Strong statistically significant (+) association between work satisfaction and life expectancy
(c) 70% people who enjoy work shall live longer
(d) 70% association between work satisfaction & life expectancy
Not true about Chi-square test is [AIIMS June 99]
(a) Tests the significance of difference between two proportions
(b) Tells about presence or absence of an association between two variables
(c) Directly measures the strength of association
(d) Can be used when more than two groups are to be compared
In a bimodal series, if mean is 2 and median is 3, what is the mode? [AIIMS June 99]
(a) 5
(b) 2.5
(c) 4
(d) 3
The standard normal distribution [AIIMS Nov 99]
(a) Is skewed to the left
(b) Has mean = 1.0
(c) Has standard deviation = 0.0
(d) Has variance = 1.0
An investigator into the life expectancy of IV drug abusers divides a sample of patients into HIV- positive and HIV-negative groups. What type of data does this division constitute?
[AIIMS June 2000]
(a) Nominal
(b) Ordinal
(c) Interval
(d) Ratio
P-value is the probability of [AIIMS June 2000]
(a) Not rejecting a null hypothesis when true
(b) Rejecting a null hypothesis when true
(c) Not rejecting a null hypothesis when false
(d) Rejecting a null hypothesis when false
A lecturer states that the correlation coefficient between prefrontal blood flow under cognitive load and the severity of psychotic symptoms in schizophrenic patients is – 1.24. You can therefore conclude that [AIIMS June 2000]
(a) Pre-frontal blood flow under cognitive load is a good predictor of the severity of psychotic symptoms in schizophrenic patients
(b) Prefrontal blood flow under cognitive load accounts for a large proportion of the variance in psychotic symptoms in schizophrenic patients
(c) Psychosis or schizophrenia is in some way a cause or partial cause of low prefrontal blood flow under cognitive load 863 Biostatistics Biostatistics Biostatistics
(d) The lecturer has reported the correlation coefficient incorrectly
Central value of a set of 180 values can be obtained by [AIIMS Nov 2000]
(b) 90th percentile
(a) 2nd tertile
(c) 9th decile
(d) 2nd quartile
The number of malaria cases reported during the last 10 years in a town is given below, 250, 320, 190, 300, 5000, 100, 260, 350, 320, and 160 The epidemiologist wants to find out the average number of malaria cases reported in that town during the last 10 years. The most appropriate measure of average for this data will be [AIIMS May 2001, AIIMS Nov 2004]
(a) Arithmetic mean
(b) Mode
(c) Median
(d) Geometric mean
In a particular trial, the association of lung cancer with smoking is found to be 40% in one sample and 60% in another. What is the best test to compare the results? [AIIMS May 2001]
(a) Chi Square Test
(b) Fischer Test
(c) Paired t Test
(d) ANOVA Test
What can be true regarding the coefficient of correlation between IMR and economic status?
(a) r = + 1 [AIIMS May 2001]
(b) r = – 1
(c) r = + 0.22
(d) r = – 0.8
Standard deviation of means measures [AIIMS May 01]
(a) Non-sampling errors
(b) Sampling errors
(c) Random errors
(d) Conceptual errors
Among a 100 women with average Hb of 10 gm%, the standard deviation was 1, what is the standard error? [AIIMS May 01, 04, 07]
(a) 0.01
(b) 0.1
(c) 1
(d) 10
A study was undertaken to assess the effect of a drug in lowering serum cholesterol levels. 15 obese women and 10 non-obese women formed the 2 limbs of the study. Which test would be useful to correlate the results obtained?
(a) ANOVA test [AIIMS Nov 01]
(b) Student’s t-test
(c) Chi square test
(d) Fischer test
The incidence of malaria in an area is 20, 20, 50, 56, 60, 5000, 678, 898, 345, 456. Which of these methods is the best to calculate the average incidence? [AIIMS Nov 01]
(a) Arithmetic mean
(b) Geometric mean
(c) Median
(d) Mode
A randomised trial comparing the efficacy of two drugs showed a difference between the two with a p value of <0.005. In reality, however the two drugs do not differ. This therefore is an example of
(a) Type I error (alpha error) [AIIMS Nov 02]
(b) Type II error (beta error)
(c) 1 – a (alpha)
(d) 1 – b
A test which produces similar results when repeated, but values obtained are not close to actual/true value, is [AIIMS Nov 02]
(a) Precise but inaccurate
(b) Precise and accurate
(c) Imprecise and accurate
(d) Imprecise and inaccurate
When a diagnostic test is used in “series” mode, then [AIIMS Nov 02]
(a) Sensitivity increases but specificity decreases
(b) Specificity increases but sensitivity decreases
(c) Both sensitivity and specificity increase
(d) Both sensitivity and specificity decrease
The number of patients required in a clinical trial to treat a specify disease increases as
[AIIMS Nov 02]
(a) The incidence of the disease decreases
(b) The significance level increases
(c) The size of the expected treatment effect increased
(d) The drop-out rate increases
The usefulness of a screening test depends upon its- [AIIMS May 03]
(a) Sensitivity
(b) Specificity
(c) Reliability
(d) Predictive value
An investigator wants to study the association between maternal intake of iron supplements (Yes/ No) and birth weights (in grams) of newborn babies. He collects relevant data from 100 pregnant women and their newborns. What statistical test of hypothesis would you advise for the investigator in this situation? [AIIMS May 03]
(a) Chi-Square test
(b) Unpaired or independent t-test
(c) Analysis of Variance
(d) Paired t-test
For testing the statistical significance of the difference in heights of school children
[AIIMS May 2003]
(a) Student’s ‘t’ test
(b) Chi-squared test
(c) Paired ‘t’ test
(d) One way analysis of variance (one way ANOVA)
The fasting blood levels of glucose for a group of diabetics is found to be normally distributed with a mean of 105 mg per 100 ml of blood and a standard deviation of 10 mg per 100 ml of blood. From this data is can be inferred that approximately 95% of diabetics will have their fasting blood glucose levels within the limits of: [AIIMS Nov 2003]
(a) 75 and 135 mgs
(b) 85 and 125 mgs
(c) 95 and 115 mgs
(d) 65 and 145 mgs
An investigator wants to study the association between maternal intake of iron supplements (Yes or No) and incidence of low birth weight (< 2500 or > 2500) grams). He collects relevant data from 100 pregnant women as to the status of usage of iron supplements and the status of low birth weight in their newborns. The appropriate statistical test of hypothesis advised in this situation is
[AIIMS Nov 03]
(a) Paired – t-test
(b) Unpaired or independent t-test
(c) Analysis of variance
(d) Chi – Square test
Mean and standard deviation can be worked out only if data is on [AIIMS Nov 03, AIIMS May 05] (a) Interval/Ratio scale
(b) Dichotomous scale
(c) Nominal scale
(d) Ordinal scale
After applying a statistical test, an investigator gets the ‘P value’ as 0.01. it means that [AIIMS Nov 2003, AIIMS May 05, 08]
(a) The probability of finding a significant difference is 1%
(b) The probability of declaring a significant difference is 1%
(c) The difference is not significant 1% times and significant 99% times
(d) The power of the test used is 99%
Sampling method used in assessing immunization status of children under immunization program is (a) Systematic sampling [AIIMS May 2004]
(b) Stratified sampling
(c) Group sampling
(d) Cluster sampling
All are true Except - [AIIMS May 04]
(a) Alpha is the maximum tolerable probability of type-I error
(b) Beta is the probability of type-II error
(c) When Null Hypothesis is true but is rejected, it is Type-II error
(d) P-value can be more or less than alpha
Statistical Power of a trial is equal to [AIIMS Nov 04]
(a) 1 + a
(b) 1 – b
(c) a + b
(d) a / b
In a 3 x 4 contingency tables, the number of degrees of freedom equals to [AIIMS Nov 2004]
(a) 1
(b) 5
(c) 6
(d) 12
In assessing the association between maternal nutritional status and the birth weight of the newborns, two investigators A and B studied separately and found significant results with p values 0.02 and 0.04 respectively. From this information, what can you infer about the magnitudes of association found by the two investigations? [AIIMS Nov 2004]
(a) The magnitude of association found by investigator A is more than that found by B
(b) The magnitude of association found by investigator B is more than that found by A
(c) The estimates of association obtained by A and B will be equal, since both are significant
(d) Nothing can be concluded as the information given is inadequate
Pearson or spearman coefficient is used for evaluation of: [AIIMS Nov 04]
(a) Differences in proportion
(b) Comparison of more than 2 means
(c) Comparison of variance
(d) Correlation
Sensitivity for a test ‘X’ is 0.90 and Specificity is .50. Prevalence of disease ‘Y’ in a population is 10%. Post-test probability of test ‘X’ when applied to population ‘Y’ is - [AIIMS May 05]
(a) 0.90
(b) 0.84
(c) 0.16
(d) 0.10
A bacterium can divide every 20 minutes. Beginning with a single individual, how many bacteria will be there in the population if there is exponential growth for 3 hours? [AIIMS May 05]
(a) 18
(b) 440
(c) 512
(d) 1024
The distribution of random blood glucose measurements from 50 first year medical students was found to have a mean of 3.0 mmol/litre with a standard deviation of 3.0 mmol/litre. Which of the following is a correct statement about the shape of the distribution of random blood glucose in these first year medical students? [AIIMS Nov 2005]
(a) Since both mean and standard deviation are equal, it should be a symmetric distribution
(b) The distribution is likely to be positively skewed
(c) The distribution is likely to be negatively skewed
(d) Nothing can be said conclusively
A chest physician observed that the distribution of forced expiratory volume (FEV) in 300 smokers had a median value of 2.5 litres with the first and third quartiles being 1.5 and 4.5 litres respectively. Based on this data how many persons in the sample are expected to have a FEV between 1.5 and 4.5 litres? [AIIMS Nov 05]
(a) 7.5
(b) 150
(c) 225
(d) 300
If the distribution of intra-ocular pressure (IOP) seen in 100 glaucoma patients has an average 30 mm with a SD of 1.0, what is the lower limit of the average IOP that can be expected 95% of times? [AIIMS Nov 05]
(a) 28
(b) 26
(c) 32
(d) 259
In the WHO recommended EPI Cluster sampling for assessing primary immunization coverage, the age group of children to be surveyed is
(a) 0-12 months [AIIMS Nov 2005]
(b) 6-12 months
(c) 9-12 months
(d) 12-23 months
Height of group of 20 Boys aged 10 years was 140 + 13 cm & 20 girl of same age was 135 cm + 7cm to test the statistical significance of difference in height, test applicable is [AIIMS Nov 05]
(a) X2
(b) Z
(c) t
(d) F
(a) Nominal
(b) Continuous
(c) Discrete
(d) Any of above
A randomised trial comparing efficacy of two regimens showed that difference is statistically significant with p<0.001 but in reality the two drugs do not differ in their efficacy. This is an example of- [AIIMS May 2006]
(a) Type-I error (a error)
(b) Type – II error (b error)
(c) 1-a
(d) 1-b
You have diagnosed a patient clinically as having SLE and ordered 6 tests. Out of which 4 tests have come positive and 2 are negative. To determine the probability of SLE at this point, you need to know- [AIIMS May 2006]
(a) Prior probability of SLE; sensitivity and specificity of each test
(b) Incidence of SLE and predictive value of each test
(c) Incidence and prevalence of SLE
(d) Relative risk of SLE in this patient
A diagnostic test for a particular disease has a sensitivity of 0.90 and a specificity of 0.80. A single test is applied to each subject in the population in which the diseased population is 30%. What is the probability that a person, negative to this test, has no disease? [AIIMS May 2006]
(a) Less than 50%
(b) 70%
(c) 95%
(d) 72%
In a given data, degree of freedom will be
Duration of developing AIDS Blood group A B AB O
0 – 5 years 20 30 48 7
5 – 10 years 110 12 37 12
10 – 15 years 12 9 8 3
[AIIMS May 06]
(a) 12
(b) 6
(c) 9
(d) 20
If the birth weight of each of the 10 babies born in a hospital in a day is found to be 2.8 kg, then the standard deviation of this sample will be [AIIMS May 2006, Dec 97]
(a) 2.8
(b) 0
(c) 1
(d) 0.28
LJ chart is used for: [AIIMS May 07]
(a) Accuracy
(b) Precision
(c) Odds
(d) Likelihood ratio
Which is the best method to compare the results obtained by a new test and a gold standard test?
(a) Correlation study [AIIMS May 07]
(b) Regression study
(c) Bland and Altman analysis
(d) Kolmogorov-Smirnov test
Sensitivity of a screening test ‘X’ is 90 % while its specificity is 10 %. Likelihood ratio for a positive test is - [AIIMS May 07]
(a) 9.0
(b) 8.0
(c) 1.0
(d) 0.1
If a 95% Confidence Interval for prevalence of Cancer in Smokers aged >65 years is 56% to 76%, the chance that the prevalence could be less than 56% is [AIIMS May 07]
(a) Practically NIL
(b) 44%
(c) 2.5%
(d) 5%
In a group of 100 children, the mean weight of children is 15 kg. The standard deviation is 1.5 kg. Which one of the following is true? [AIIMS May 2007]
(a) 95% of all children weight between 12 and 18 kg
(b) 95% of all children weight between 13.5- and 16.5kg
(c) 99% of all children weight between 12 and 18 kg
(d) 99% of all children weight between 13.5 and 16.5kg
Which is the best distribution to study the daily admission of head injury patients in a trauma care centre? [AIIMS May 2008]
(a) Normal distribution
(b) Binomial distribution
(c) Uniform distribution
(d) Poisson distribution
Mean bone density amongst 2 group of 50 people each is compared, which would be the best test?
(a) Chi square [AIIMS May 2008]
(b) Student t test
(c) Mcnemar chi square test
(d) Fischer test
Association can be measured by all except
(a) Correlation coefficient [AIIMS May 2009]
(b) Cronbach’s alpha
(c) P value
(d) Odds ratio
The risk factor association of smoking with pancreatic cancer was studied in a case control study. The values are
Group Odds ratio 95% Confidence limits
A 2.5 1.0 – 3.1
B 1.4 1.1 – 1.7
C 1.6 0.9 – 1.7
Which of the following is correct [AIIMS Nov 09]
(a) Risk is more associated with Group A
(b) Risk is more associated with Group B
(c) Risk is more associated with Group C
(d) Risk is equally associated with all three groups
All of the following are true about Standard error except? [AIIMS Nov- 09]
(a) As the sample size increases, Standard error will also increase
(b) Based on Normal distribution
(c) It depends on Standard deviation of mean
(d) Is used to estimate confidence limit
In a study following interpretation are obtained: Satisfied, Very satisfied, Dissatisfied. Which type of scale is this? [AIIMS May 2010]
(a) Nominal
(b) Ordinal
(c) Interval
(d) Ratio
Which of the following is used to denote a continuous variable? [AIIMS May 2010]
(a) Simple bar
(b) Histogram
(c) Pie diagram
(d) Multiple bar
In a study following interpretation are obtained: Satisfied, Very satisfied, Dissatisfied. Which type of scale is this? [AIIMS May 2010]
(a) Nominal
(b) Ordinal
(c) Interval
(d) Ratio
True about cluster sampling all except [AIIMS May 2011]
(a) Sample size same as simple random
(b) It is two stage sampling
(c) Cheaper than other methods
(d) It is a method for rapid assessment
An investigator finds out that 5 independent factors influence the occurrence of a disease. Comparison of multiple factors that are responsible for the disease can be assessed by:
[AIIMS May 2011]
(a) ANOVA
(b) Multiple linear regression
(c) Chi-square test
(d) Multiple logistic regression
Method used for comparison of a new test with an available gold-standard test is
[AIIMS November 2011]
(a) Regression analysis/Likelihood test
(b) Correlation analysis/Bland and Altmann test
(c) Baltin and Altimore method
(d) Kimorov and Samletor technique
In a study first schools are sampled, then sections, and finally students. This type of sampling is known as: [AIIMS November 2012]
(a) Stratified sampling
(b) Simple random sampling
(c) Cluster sampling
(d) Multistage sampling
50% population having disease with estimated prevalence to be 45-55% with 95% of probability of identifying them minimum sample size required is:
(a) 100 [AIIMS May 2013]
(b) 200
(c) 300
(d) 400
If confidence limit is increased, then: [AIIMS May 2013]
(a) Previously insignificant data becomes significant
(b) Previously significant data becomes insignificant
(c) No effect on significance
(d) Any change can happen
In a population of 100 prevalence of candida glabrata was found to be 80%. If the investigator has to repeat the prevalence with 95% confidence what will the prevalence be? [AIIMS May 2013]
(a) 78-82%
(b) 76-84%
(c) 72-88%
(d) 74-86%
How much population falls between median and median plus one standard deviation in a normal distribution? [AIIMS Nov 2013]
(a) 0.34
(b) 0.68
(c) 0.17
(d) 0.47
There is a population of 20000 people with mean haemoglobin being 13.5 gm% having a normal distribution. What proportion of population constitutes proportion more than 13.5 gm%?
[AIIMS Nov 2013]
(a) 0.25
(b) 0.50
(c) 1
(d) 0.34
Q-test is used for detecting: [AIIMS Nov 2013]
(a) Outliers
(b) Interquartile range
(c) Difference of means
(d) Difference of proportions
ANSWERS ARE IN RED!
PSM / COMMUNITY MEDICINE by Dr Abhishek Jaiswal is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
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