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Biostatistics Question Paper
Biostatistics
Course:Bachelor Of Education Science
Institution: Kenyatta University question papers
Exam Year:2010
KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2009/2010
INSITUTIONAL SCHOOL BASED PROGRAMME
EXAMINATION FOR THE DEGREE OF BACHELOR OF EDUCATION (SCIENCE)
SZL 300: BIOSTATISTICS
DATE: WEDNESDAY 28TH APRIL 2010
TIME: 8.00A.M – 10.00A.M
INSTRUCTIONS:
Attempt ALL questions in Section A and any ONE question in Section B. In each section
all questions carry equal marks. Illustrate your answers with diagrams and give examples
where appropriate.
SECTION ONE (Attempt ALL questions) 40 marks
1.
Define the term ‘statistics’ clearly explaining what are ‘statistical’ and ‘non- statistical’ facts.
2.
Using hypothetical biological data for illustration, distinguish between discrete and continuous random variables.
3.
The incidence of occupational disease in an industry is such that the workers have a 20% chance of suffering from it. What is the probability that out of six workers, 4 or more will contract the disease?
4.
The mean and standard deviation of a set of 100 laboratory observations were worked out as 40 and 5 respectively by a computer which by mistake took the value of 50 in place of 40 for one of the observations. Find the correct mean and variance.
5.
Correlation does not necessarily imply causation though the existence of causation always implies correlation. Explain this statement within the context of biological data.
6.
A research involving a sample of 100 patients taking ARVs revealed that the average cost of the drugs per month is $253 with a standard deviation of $70. Calculate the 95% confidence interval for the mean cost of the ARVs. [5 marks]
7.
A sample of 200 people with a particular disease was selected out of these, 100 were given a drug and the others were not given any drug. The results are as follows:
Number of people
Drug
No
Drug
Total
Cured 65 55 120
Not cured
35
45
80
Total
100
100
200
At 5% level of significance, test whether the drug is effective.
8.
a)
State two assumptions in statistical Analysis of Variance
b)
Distinguish between type - I and type - II error in hypothesis testing
SECTION B: Answer any ONE question (30 marks)
9.
a)
Four different drugs have been developed for a certain disease. These drugs are used in three different hospitals and the results, given below, show the number of cases of recovery from the disease per 100 people who have taken the drug.
Type of drug
Hospital D1 D2 D3 D4
H1
19 8 23 8
H2
10 9 12 6
H3
11 13 13 10
i)
Formulate appropriate hypotheses for ANOVA of this scenario.
ii)
From ANOVA, draw appropriate conclusions.
b)
A researcher is interested in establishing the degree of association between Aptitude and Age. To obtain data for his study he invited and interviewed ten applications for a job and ranked them in order of preference from 1 (lowest) to 10 (highest). The ten applicants also sat an aptitude test. The researcher’s rankings, the aptitude scores and the applicant’s ages are shown below.
Applicant: A B C D E F G H I J
Ranking: 5.5
7 2 10 9 1 3 8 5.5
4
Aptitude: 105 110 90 120 125 95 100 120 110 110
Age:
35 24 45 20 20 40 30 18 35 22
a)
Find the Pearson correlation coefficient between Aptitude and Age and comment on the result.
b)
Find the equation of the least-squares regression line, assuming that Aptitude is the dependent variable (y) and Age is the independent variable (x).
c)
Comment on the usefulness of the regression equation estimated in part (b).
d)
Rank the aptitude scores, giving 1 to the lowest score and 10 to the highest.
e)
Calculate Spearman’s rank correlation coefficient between the interviewer’s rankings and the aptitude rankings, and interpret the result.
10.
a)
A Medical lab manager wishes to know what proportion of all lab tests that had been conducted in the lab gave false results. He requires a 99% confidence interval. To obtain the findings, a random sample of 500 test results was selected. From the sample, 76 test results were false. Calculate the 99% C.I.
b)
Assume that half of a population of people under a study is vegetarian. From a sample of 10 determine the probability that three people or less are vegetarians.
c)
Prove that the mean and variance of the Poisson distribution are equal.
d)
Distinguish between parametric and non-parametric probability distributions.
e)
A researcher is interested in establishing whether there is any significant association between inoculation and disease attack. The following data were collected.
Not
Attacked Total
attacked
Inoculated 506
494
1000
Not
438 162 600
inoculated
Total 944
656
1600
i)
Formulate appropriate hypotheses.
ii)
At 5% significance level, test the hypotheses that inoculation and attack are associated.
f)
Differentiate between the following terms in biostatistics:
i)
Census and sampling
ii)
Population parameter and sample statistics
iii)
Point estimation and interval estimation
iv)
Null hypothesis and alternative hypothesis
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