Biostat 324-final 2005

(B. Sc. Biochemistry) Sixth Semester 2005 Subject: Biostat 324 (Biostatistics)

Full Marks: 100 Pass Marks: 45 Time: 3 hours

Candidates are required to give their answers in their own words as far as practicable. The figure in the margin indicates full marks. Group (A) Long Questions (Any three)

(3× ×14 = 42)

1. Explain the role of statistics in preventive medicine. Also discuss the types of biological data. 2. A scientist doing research on a special type of fodder which helps to increase the weight of animals in short period, kept of 100 bulls under experiment those bulls were given a fixed amount of developed fodder per day for one month and after one month they were weighted. Following table gives the increase in their weight after the experiment. Increase in wt (in kg.): 0-5 5-10 10-15 15-20 20-25 25-30 30-35 No. of bulls 3 7 18 35 25 8 4 The scientist is confident that if the data obtained fits a normal curve, he is successful in developing the special fodder. Do you think the scientist is successful in his endeavour? 3. a. Prevalence of diabetes in a community is one diabetic case in 10 persons. If 4 children are born what will be the probability of occurrence of diabetes in the following combinations: (i) All the 4 normal (ii) 2 diabetic and 2 normal (iii) All the 4 children born diabetic b. There are 20% chances for a worker of an industry to suffer from an occupational disease. 50 workers were selected at random and examined for the occupational disease. Find the probability that: (i) Only one worker is found suffering from the disease. (ii) None is suffering from the disease. 4. Experience shows that a fixed dose of a certain drug causes an average increase of pulse rate of 10 beats per minute with a standard deviation of 4. A group of 9 patients given the same dose showed the following increase: 13, 15, 14, 10, 8, 12, 16, 9, 20 Test at 5% level of significance whether this group is different in response to the drug? [t 0.05 (8) = 2.31] Group (B) Short Questions: (Any six)

(6× ×7 = 42)

1. Explain the advantages and disadvantages of clinical trials. 2. Explain the scope of statistical methods in medicine. 3. The following data gives the marks obtained by 10 students in Biostatistics and Microbial Biochemistry. Marks in Biostatistics 45 70 65 30 90 40 50 75 85 60 Marks in Microbial Biochemistry: 35 90 70 40 95 40 60 80 80 50 Find the correlation coefficient and interpret it. 4. During 10 weeks of a session, the marks scored by two candidates A and B taking Biostatistical Training course are given below: A: 58 59 60 54 65 66 52 75 65 52 B: 87 89 78 71 73 84 65 66 56 46 Who is more consistent? 5. Write short notes on estimation. 6. A husband and wife appear in an interview for two vacancies in the same post. The probability of husband's selection is 1/7 and that of wife selection is 1/5. What is the probability:

(i) Both of them will be selected and (ii) Only one of them will be selected. 7. Calculate coefficient of variation of the Erythrocyte Sedimentation rate (ESR), found to be 3, 4, 5, 4, 2, 4, 5 and 3 in 8 normal individuals. 8. Calculate the rank correlation coefficient between X and Y for the following data: X: 92 89 87 86 83 77 71 63 53 50 Y: 86 83 91 77 68 85 52 82 37 57 Group (C) Very Short Questions: (Any eight)

(2× ×8 = 16)

1. What do you mean by meta analysis? 2. Explain Biostatistics in medicine. 3. The following data show the number of children born to 350 women: No. of Children: 0 1 2 3 4 5 6 No. of women: 171 82 50 25 13 7 2 Calculate the mean number of children born per woman. 4. A student calculates the value of r as 0.81 when the value of n is 10 and concludes that r is highly significant. Is his conclusion correct? 5. What are the chances of getting any combination i.e. 2 boys, 2 girls or one boy and one girl when number of pregnancies is 2? 6. Problem of biostatistics is given to three students A, B and C whose chance of solving it are 1/2, 1/3 and 1/4 respectively. Find the probability that the problem will be solved. 7. Write short notes on testing of hypothesis. 8. Explain Binomial distribution. 9. Explain sampling distribution. 10. Calculate Karl Pearson's correlation coefficient between X and Y from the following data: n = 11, x = 117, x2 = 1313, y = 260, y2 = 6580, xy = 2827. 11. Coefficient of variation for series are 75% and 90% and their standard deviations 15 and 18 respectively. Find their means. 12. Oral surgery unit of a dental college performed the following number of operations each month. Find the range and mean of monthly operations: ***