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Biostatistics Question Paper

Biostatistics

Course:Microbiology And Biotechnology

Institution: University Of Nairobi question papers

Exam Year:2014

UNIVERSITY OF NAIROBI
FIRST SEMESTER EXAMINATIONS 2008/2009
THIRD YEAR EXAMINATIONS FOR THE DEGREE OF BACHELOR OF SCIENCE
SZL 303: BIOSTATICS
DATE: 17 FEBRUARY, 2009 TIME: 9:00 A.M. – 12.00 NOON
SECTION A
INSTRUCTIONS: Answer all questions (3 marks each)
1. Distinguish between stratified random sampling and simple random sampling.
2. What processes lead to the following distributions:
i. Rectangular distributions:
ii. Normal distribution
3. Calculate the median for the following sample 20.1,2.3, 4.4, 6.5, 10.6, 20.1
4. Distinguish between binomial and Poisson distribution.
5. What problems arise from carrying out multiple t-tests rather than ANOVA for more than two samples?
6. Distinguish between correlation coefficient and coefficient of determination.
7. Under what circumstances in the chi-square analysis are the following undertaken:
i. Yates correction
ii. Heterogeneity testing
8. What do you understand by the following terms:
i. Degrees of freedom
ii. Sampling distribution
9. Attach confidence intervals for the following normally distributed sample:
Mean = 2.65kg sample size = 112 standard deviation = 4.6 kg
10. List the assumptions of parametric statistical testing.
SECTION B Answer any two questions (20 marks each)
11. The following are weights n kg of sheep reared under a given dietary regime on two ranches in Machakos district:
Konza 36.7 42.5 35.2 38.7 41.6 36.9 39.5
Kiu 29.7 26.5 28.8 30.4 21.8 27.6 32.8 27.5
i. Test whether the weights were significantly different (16 marks)
ii. Why is the normal distribution regarded as a special case of the t- distribution? (2 marks)
iii. Explain why the paired t-test is regarded as a more powerful test compared to he ordinary two sample t-test. (2 marks)
12. A researcher carried out an investigation on yields by 4 maize varieties at the KARI research station, Kiboko. The following yields in kg/ha were obtained:
Variety 1 variety 2 variety 3 variety 4
430.4 392 344 356
398 388.6 356.4 338
412 376.4 360.8 346
406 381.5 358.4 330
419 348.2 332
416 325
? Test whether the yield differed significantly between the four varieties. (16 marks)
? Distinguish between the randomized complete block design and the Latin design in ANOVA analysis. (2 marks)
? Explain why the ANOVA is regarded as a robust test. (2 marks)

13. A restoration forest patch planted with four species was infested by an exotic variety of a fungus. The following data was obtained:
Species

Infection A.mellifrea A.niltica A.kirkii A.xanthophloea
Not infected 20 50 10 15
infected 12 23 30 45

i. Test whether infection was independent of species. (16 marks)
ii. Why is the chi-square test regarded as the goodness of fit test? (2 marks)
iii. Describe the errors associated with statistical hypothesis testing. (2 marks)
14. Discuss the importance of statistics in biological investigations citing different scenarios and the tests that can be used in them. (20 marks)

Biostatistics Question Paper

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