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Biostatistics Question Paper
Biostatistics
Course:Microbiology And Biotechnology
Institution: University Of Nairobi question papers
Exam Year:2014
UNIVERSITY OF NAIROBI
UNIVERSITY EXAMINATIONS 2009/2010
THIRD YEAR EXAMINATIONS FOR THE DEGREE OF BACHELOR OF SCIENCE
SZL 303: BIOSTATISTICS
DATE: 17 FEBRUARY, 2010 TIME: 9:00 A.M. – 12.00 NOON
SECTION A
INSTRUCTIONS: Answer all questions (3 marks each)
1. Outline the advantages of stratified random sampling.
2. i. Define the power of a test. ii. In what ways can a test be made more powerful.
3. Distinguish between parametric and non- parametric statistics.
4. i. What do you understand by a sampling distribution?
ii. Distinguish between acceptance and rejection regions in statistical testing.
5. To what type of data is logarithmic transformation applied?
6. Compare and contrast the normal and t - distributions.
7. i. Define the terms degree of freedom.
ii. Calculate the df for a 5x6 contingency table.
8. Test whether a student with an IQ of 75 comes from a group of students with an IQ of 95 and a standard deviation of 6.
9. What do you understand by robust estimator. Give two examples.
10. Explain the properties of hypothesis used in statistical testing.
SECTION B Answer any two questions
11. A drug under development was claimed to induce weight loss. A group of volunteers took one drug and the following weight differences (kg) were obtained for before and after case tests:
-3.1, 4.6, 2.0, 0.1, -4.2, -3.6, 1.2, -1.4, 2.6, 0
i. Test whether there was a significant weight difference (16 marks)
ii. Why is the paired t-test regarded as a more powerful test than the ordinary t-test? (2 marks)
iii. Distinguish between the one tailed and the two tailed scenarios in t-test analysis. (2 marks)
12. The following is data on the distribution of a weaver bird species in Tsavo National Park.
Class Wet Wet/Dry Dry Dry/Wet
Adult male 140 116 -80 125
Adult female 120 114 95 60
Juvenile male 35 52 45 80
Juvenile female 60 40 20 37
i. Use the Chi-square test to determine whether the species was evenly distributed in all the seasons.
ii. Why is the chi-square regarded as goodness of fit test?
iii. Under what circumstances is the heterogeneity chi-square performed.
13. The following data is on yield maize (Kg/ha) in soils with different Ph
pH 6.5 10.4 7.1 9.2 5.0 4.2 5.6 8
Yield 140 96 125 80 72 65 125 65
i. Carry out a correlation analysis and test the significance of r.
ii. Why does the correlation coefficient range between -1 and + 1?
iii. Distinguish between correlation and regression analysis?
20. Giving examples, discuss the use of various statistical tests in biological studies. (20 marks)
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