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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
ME SEMESTER-1 EXAMINATION WINTER 2018
Subject Code: 3713112 Date: 01/01/2019
Subject Name: Biostatistics
Time: 02:30 PM To 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full mark
Q.1 Discuss the various types of data and sources of data in the field of Biostatistics. 07
Explain various measurement scales with necessary examples. 07
Q.2 Explain coefficient of variation. "Standard deviation may yield more appropriate measure
of variation than coefficient of variation." True or False? Justify answer with appropriate
example.
07
A case-control study was conducted in Auckland, New Zealand, to investigate the effects
among regular drinkers of alcohol consumption on both nonfatal myocardial infarction
and coronary death in the 24 hours after drinking. Data were tabulated separately for men
and women.
A. Refer to the myocardial infarction data. Calculate separately for men and women the
odds ratio associated with drinking.
B. Compare the two odds ratios in part When the difference is confirmed properly,
we have an effect modification.
C. Refer to coronary deaths. Calculate separately for men and women the odds ratio
associated with drinking.
D. Compare the two odds ratios in part When the difference is confirmed properly,
we have an effect modification.
07
OR
2
Below given table lists the number of deaths due to a variety of causes among Gujarat
residents for the years 2005-2010. After calculating the proportion of deaths due to each
cause: (Assume that other causes do not include any deaths due to medical conditions.)
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A. Calculate and prepare a table of the relative frequency of each cause of death.
B. Prepare a pie diagram to show the distribution of cause of death.
C. What might be the probability that a person dies with some medical dieses?
D. Suppose that an insurance company sells life insurance to 10,00,000 persons of total
population of Gujarat. Suppose also that the insurance covers for Rs. for
accidental death and Rs. for any medical condition. What annual rate
would the insurance company have to charge to break even?
Q.3 Explain the concept of estimation and confidence level with appropriate examples. 07
A cytological test was undertaken to screen women for cervical cancer. Consider a group
of 24,103 women consisting of 379 women whose cervices are abnormal (to an extent
sufficient to justify concern with respect to possible cancer) and 23,724 women whose
cervices are acceptably healthy. A test was applied and results are given in table.
A. Find the sensitivity and specificity of the test. Also comment the results.
B. If a woman with cervical cancer is tested, what are the chance that the disease would
go undetected? Why?
C. Calculate the positive predictive values and negative predictive values when the test is
applied to the following populations:
a. Population 80% prevalence
b. Population 25% prevalence
07
OR
Q.3 Explain PDF and CDF with necessary examples. 07
3
A study on the effects of exercise on the menstrual cycle provides the following ages
(years) of menarche (the beginning of menstruation) for 96 female swimmers who began
training prior to menarche.
A. Form a frequency distribution having 6 groups, including relative frequencies and
cumulative relative frequencies.
B. Plot the frequency polygon and cumulative frequency graph.
C. Find the median and 95th percentile.
D. Plot a stem-and-leaf plot.
07
Q.4 Describe the interpretation of the sample correlation coefficient with appropriate
equations.
07
In a study of intraobserver variability in assessing cervical smears, 3325 slides were
screened for the presence or absence of abnormal squamous cells. Each slide was
screened by a particular observer and then rescreened six months later by the same
observer. The results are shown in below table.
A. The probability that abnormal squamous cells were found to be absent in both
screenings.
B. The probability of an absence in the second screening given that abnormal cells were
found in the first screening.
C. The probability of an abnormal presence in the second screening given that no
abnormal cells were found in the first screening.
D. The probability that the screenings disagree.
E. Find sensitivity and specific of both tests.
F. Also, find the predictive value positive and predictive value negative assuming that
42% of the slides are having abnormal squamous cells.
G. What is the prior and posterior probabilities of cervical smears given that both
observers have reported presence of abnormal squamous cells?
07
OR
Q.4 Explain dichotomous covariates and Continuous covariates with examples for
multivariate regression analysis.
07
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The following are the menarchal ages (in years) of 56 female swimmers who began
training after they had reached menarche.
A. Prepare an ordered data table.
B. Form a frequency distribution table using the age intervals as given below.
a. Range 10-17 and Class Interval 0.5
b. Range 12-16 and Class Interval 0.2
C. Draw the Histogram and Frequency Polygon curves.
D. Draw Stem-and-leaf plot.
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Q.5 Give the difference of One-Sided versus Two-Sided Tests with necessary examples. 07
Compute the probability that the mean birthweight from a sample of 10 infants from the
Boston City Hospital population will fall between 98.0 and 126.0 oz (i.e.,98 X 126) if
the mean birthweight for the 1000 birthweights from the Boston City Hospital population
is 112.0 oz with a standard deviation of 20.6 oz. (Assume the normal value to be 0.9842.)
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Q.5 Explain the difference between H0 and HA. For each part, state the H0 and HA.
A. Has the average community level of suspended particulates for the month of August
exceeded 30 mg/cm3?
B. Does the mean age of onset of a certain acute disease for school children differ from
11.5?
C. A psychologist claims that the average IQ of a sample of 60 children is significantly
above the normal IQ of 100.
D. Is the average cross-sectional area of the lumen of coronary arteries for men, ages 40-
59, less than 31.5% of the total arterial cross section?
E. Is the mean hemoglobin level of high-altitude workers different from 16 g/cm3?
F. Does the average speed of 50 cars as checked by radar on a particular highway differ
from 55 mph?
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5
Below given table shows Body Mass Index Data for a Sample of 120 Adults: Ordered
Array (Sorted in Ascending Order).
Prepare a table and draw histogram graphs of below listed values for
mentioned seven intervals.
1. 18.0 20.9
2. 21.0 23.9
3. 24.0 26.9
4. 27.0 29.9
5. 30.0 32.9
6. 33.0 35.9
7. 36.0 38.9
A. Frequency f
B. Cumulative Frequency f
C. Relative Frequency
D. Cumulative Relative Frequency
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