SRM University 2007 B.Tech Bioinformatics BIO-INFORMATICS BANK MA262 (BIO STATISTICS) - Question Paper

S.R.M.INSTITUTE OF SCIENCE & TECHNOLOGY
II – YEAR B.TECH – BIO-INFORMATICS
ques. BANK
MA262 (BIO STATISTICS)
UNIT: V
PART-A


1) Define correlation and state the formula for Karl Pearson’s coefficient of correlation.
2) State any 2 properties of correlation coefficient.
3) What is rank correlation. provide its formula and also provide the correction factor when the ranks are repeated.
4) The coefficient of rank correlation of the marks found by 10 students(where no 2 ranks are same) in two subjects was 0.5.It was later discovered that the difference in ranks in 2 subjects found by 1 of the students was wrongly taken as three instead of 7.Find the accurate coefficient of rank correlation.
5) Write the lines of regression of X on Y and Y on X and also write the regression coefficients.
6) Write any 2 Properties of regression coefficients.

7) Can y=5+2.8x and x=3-0.5y be the regression lines of Y on X and X on Y respectively. provide suitable arguments.
8) The 2 lines of regression are x+2y-5=0 and 2x+3y=8.Find the mean values of X &Y.
9) If bxy and byx are the regression coefficients of X on Y and Y on X then P.T.(i) r = ?bxy*byx (ii)if bxy>1 then byx<1
10) Write the formula for finding the angle ranging from 2 lines of regression.

PART-B


1. Ten competitors in a musical test were ranked by 3 judges X,Y,Z in the
subsequent order

I II III IV V VI VII VIII IX X
Rank by X 1 6 5 10 3 2 4 9 7 8
Rank by Y 3 5 8 4 7 10 2 1 6 9
Rank by Z 6 4 9 8 1 2 3 10 5 7
Using rank correlation method explain which pair of judges has the closest approach to common likings of music.

2. Calculate the correlation coefficient ranging from the provided data.
X : six 10 12 four 15 12 14 eight seven 5
Y : three three four one five three three two two 2

3. Obtain the rank correlation coefficient for the subsequent data.
X : 68 64 75 50 64 80 75 40 55 64
Y : 62 58 68 45 81 60 68 48 50 7

4. From the subsequent data obtain the regression equations and the most likely marks in statistics when the marks in economics is 30.
Marks in Economics : 25 28 35 32 31 36 29 38 34 32
Marks in Statistics : 43 46 49 41 36 32 31 30 33 39
5. The 2 regression equations of the variables X and Y are X= 19.13 – 0.87Y and Y = 11.64 – 0.50X.Find the mean of X and Y and also correlation coefficient ranging from X and Y.
6. While calculating correlation coefficient ranging from 2 variables X and Y from 25 pairs of observations the subsequent outcomes were found N= 25 , ?X = 125 , ?X2 = 650 , ?Y= 100 , ?Y2 = 460 , ?XY = 508 . Later it was discovered at the time of checking that the pair of values X : eight , six & Y : 12 , eight were copied down as X : six , eight & Y : 14 , six .Obtain the accurate value of correlation coefficient.

Earning:   Approval pending.