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### MCQs in Public Health Dentistry - Biostatistics

The correct answers are highlighted in green.

# The arithmetical average of a number of observations is called :
A. Mean
B. Median
C. Range

D. All of the above

# Which of the following correlates highest correlation between variables ?
A. r= + 0.25
B. r= + 0.5
C. r= - 0.75
D. r= + 2

Correlation coefficient (r) indicates the degree of correlation between two variables. Its value ranges from -1 to +1. The correlation coefficient is zero when there is no covariation between two variables.
Independent of the sign, the farther the ‘r’ value from ‘0’, the stronger the relationship, i.e. -1 indicates perfect negative correlation whereas +1 indicates a perfect positive correlation. Since 0.75 is farther from 0 than 0.25 and 0.5, option C is the correct answer.

# Which of the following is not a measure of central tendency ?
A. Mean
B. Mode
C. Range
D. Median

# Father of Health Statistics is:
A. John Snow
B. John Graunt
C. Frederick Mc Kay
D. Pierre Fauchard

# Ranking students from the individual with the highest Grade points average (GPA) to the lowest is an example of:
A. Ordinal Scale
B. Nominal Scale
C. Interval Scale
D. Ratio Scale

# # A random sample suggests that :
A. A person in a control group will not be a member of the experimental group
B. Any member of a group to be studied has an equal opportunity to be included in the study
C. Every nth name on a list is selected
D. Subjects are volunteers

# A statistical test which indicates the chance or probability of an observed difference between two means occurring by chance is called:
A. Tests of significance
B. Means
C. Ratio
D. Normalcy

# Best measure for central tendency in a highly skewed distribution is :
A. Median
B. Mean
C. Mode
D. Range

# The graphic representation of frequency distribution with X and Y axis is :
A. Frequency polygon
B. Histogram
C. Pictograph
D. Pie diagram

# A series may have all except :
A. No mode
B. One mode
C. Many modes
D. Negative mode

# The correlation coefficient can range from :
A. 0 to +1
B. 0 to -1
C. -1 to +1
D. 0 to 100

# As the sample size increases, standard deviation :
A. Decreases
B. Increases
C. Remains the same
D. May increase or decrease

# In a 3*3 table, the number of degrees of freedom is:
A. 4
B. 9
C. 3
D. 81

# Most of the values in data spread along the :
A. Mean
B. Mode
C. Median
D. Arithmetic mean

# Prevalence of diseases is: (COMEDK-2013)
a) Rate
b) Deviation
c) Proportion
d) Ratio

# The type II error is the acceptance of a null hypothesis as true when it is: (KAR-2003)
a) Negative valued
b) True
c) Nonexistent
d) False

# Standard deviation is a measure of: (KAR-98, MAN-98)
a) Statistical significance
b) Central tendency
c) Variation
d) Correlation

# Standard error of mean indicates
a) Dispersion
b) Distribution
c) Deviation
d) Variation

# In health education program, a group of 10 people are planning to speak on a single topic of common interest. Which one of the following is best educational approach? (AIPG-06)
a) Workshop
b) Panel discussion
c) Symposium
d) Group discussion

# For testing the statistical significance of the difference in heights of school children among three socio economic groups the most appropriate statistical test is: (AIIMS-2003)
a) One way analysis of variance (one way ANOVA)
b) Paired t-test
c) Student's t-test
d) Chi-squared test

# The correlation between variables A and B in a study was found to be 1.1. This indicates:  (AIPG-2002)
a) Weak correlation
b) Very strong correlation
c) Moderately strong correlation
d) Computational mistake in calculating correlation

# Which of the following is correct?
a) In negatively skewed (left skewed) distribution curve Mean < Median
b) In Positively Skewed (right skewed) distribution curve Mean > Median
c) In normal distribution curve, Mean = Median = Mode
d) All of the above

# An investigator want to know the similarity of the mean peak flow of expiratory rates and non-smokers, tight smokers, moderate smokers, and heavy smokers. Which is statistical test of significance?  (AIIMS MAY 2012)
a) Two way ANOVA
b) One way ANOVA
c) Chi square test
d) Student t-test

# Sensitivity of a test is its ability to identify: (COMEDK-2003)
a) False negative
b) True positive
c) True negative
d) False positive

# The test done for a statistically significant change in cholesterol values in a group of patients following an interventional programme is: (AIIMS-2001)
a) Unpaired "t" test
b) Paired "t" test
c) Fisher test
d) Chi square test

#  An investigator wants to study the association between maternal intake of iron supplements (Yes or No) and birth weights (in gm) of new born 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-2003)
a) Student t - test
b) Analysis of variance
c) Unpaired or independent t - test
d) Chi-square test

# Square root of pq/n indicates: (AIPG-06, AIIMS-07)
a) Standard error of proportions
b) Standard error of mean
c) Standard error of difference of means
d) Standard error of difference in proportions

# A normal distribution curve depends on
a) Range and sample size
b) Mean and sample size
c) Mean and Median
d) Mean and standard deviation

# When variables are not measurable,  which of the following is used to be represented?
a) Nominal
b) Ordinal
c) Ratio
d) Variation

# In assessing the association between maternal nutritional status and the birth weight of 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 investigators: (AIIMS-2004)
a) Nothing can be concluded as the information given is inadequate.
b) The magnitude of association found by B is more than A
c) the magnitude of association found by A is more than B
d) The estimates of association obtained by A and B will be equal, since both are significant

# A measure of location which divides the distribution in the ratio of 3:1 is: (AIPG-2003, AIIMS-06)
a) Third Quartiles
b) Mode
c) First Quartiles
d) Median

# More false positive on screening in a community signify that the
a) Test has low specificity
b) Disease has high prevalence
c) Disease has low prevalence
d) Test has high sensitivity

# The most appropriate method of testing the statistical significance of the differences between means of two groups is: (AIIMS-2001)
a) Student test
b) Multiple regression analysis
c) Chi square test
d) Correlation coefficient analysis

# Denominator while calculating the secondary attack rate includes: (AIPG-2003)
a) ALL the close contacts
b) ALL susceptible amongst close contact
c) ALL susceptible in the whole village
d) ALL the people living in next fifty houses

# Statistics to check out mean of values is done by: (AIIMS-95)
a) Chi-square test
b) Probability test
c) Horizontal studies
d) Student's analysis

# When frequency is given as mild, moderate, and severe, the data scale used is:
a) Variance
b) Interval
c) Nominal
d) Ordinal

# Which of the following is true about Chi-square test? (AIIMS-06)
a) Measures both qualitative and quantitative data
b) Measure the quantitative data between two proportion
c) Measures the qualitative data between two proportion
d) Measures qualitative data

# Which of the following condition must be met for a valid student-t test between means of two groups? (AIIMS MAY 2012)
a) Mean should be approximately same - no
b) Number of observation must be same - no
c) Sample must be small
d) Standard deviation must be approximately same - no

# In a study, variation in cholesterol was seen before and after giving a drug. The test which would give its significance is: (AIPG-2002)
a) Fisher's test
b) Paired test
c) Chi square test
d) Unpaired test

#  If the mean cholesterol value of a group of normal subjects is 230 mg% with standard error of 10. The 95% confidence limits for the population
a) 220 and 240
b) 210 and 240
c) 200 and 260
d) 210 and 250

# In a random sampling chance of being picked up is
a) Same and known
b) Not same but known
c) Same and not known
d) Not same and not known

# The usefulness of a screening test depends upon it: (AIIMS -2003)
a) Specificity
b) Reliability
c) Sensitivity
d) Predictive value

#Chi-square test is used to measure the degree of: (AIIMS-06)
a) Association between two variables
b) Correlation between two variables
c) Agreement between two observations
d) Causal relationships between exposure and effect

# Accepting the null hypothesis when it is false: (COMEDK-08)
a) Type II error
b) Type IV error
c) Type III error
d) Type-I error

# Mean weight of 100 children was 12kgs, The standard deviation was 3, Calculate the percent coefficient of variance:
a) 55%
b) 25%
c) 45%
d) 35%

# Which statement is true about normal distribution curve?
a) Curved Skewed towards left
b) Mean -1, SD - zero
c) Curved Skewed toward right
d) SD-1, Mean - zero

# Comparison of proportions can be made by: (C0MEDK-Q7, PGI JUNE- 13)
a) Correlation & Regression
b) Chi-square test
c) ANOVA
d) T test

# Study that is used to compare serum cholesterol levels in obese and non-obese women and to find the relation or significant prevalence is:
a) Paired test
b) Student Y test
c) Z- test
d) Chi-square test

# All of the following are random sampling methods except
a) Cluster sampling
b) Simple random
c) Stratified random
d) Quota sampling

# The correlation coefficient can range from: (KAR-2003)
a) 0 to -1
b) 0 to + 1
c) 0 to 100
d) -1 to +1

# The branch of biostatistics which deals with the births, deaths and marriage is called as: (KAR-04)
a) Vital
b) Health
c) Medical
d) Demography

# The best sampling procedure that can be followed is: (KAR-99)
a) Stratified random
b) Systematic
c) Simple random
d) Convenient

# Prevalence of the disease affects
a) Repeatability
b) Predictive value
c) Sensitivity
d) Specificity

# Correlation between the height and weight of children is best represented by: (AIIMS-2001)
a) Bar diagram
b) Histogram
c) Line diagram
d) Scatter diagram

# What is the characteristic of normal distribution? (AIPG-09)
a) Mean = Median = mode
b) Curve skewed towards the right
c) Curve skewed towards the left
d) Mean is 1, SD-zero

# A Gaussian distribution is: (KAR-2003)
a) Poisson distribution
b) Log normal distribution
c) Variant distribution
d) Normal distribution

# A sampling unit is defined as: (AIPG-09)
a) All of them
b) A subset of sample
c) A group of sample
d) Representing every member of sample

# Yates correction is necessary in chi-square test when expected frequency in any one cell is: (COMEDK-08)
a) Less than 10
b) More than 10
c) Less than 5
d) More than 5

# The number of dental caries cases reported during last 10 years are given below 250, 320, 190, 300, 5000, 100, 260, 350, 320 and 160. The epidemiologist wants to find out average number of caries cases reported in that town for last 10 yrs. The most appropriate average for this data will be: (AIIMS-2004)
a) Median
b) Mode
c) Geometric mean
d) Arithmetic mean

# As the sample size increases standard deviation: (KAR-2003)
a) Increases
b) Decreases
c) may increase or decrease
d) Remains the same

# When a circle is divided into different sectors corresponding to the frequencies of the variable in the distribution, the diagram is known as? (KAR-04)
a) Bar
b) Pie
c) Pictogram
d) Histogram