1
ASSIGNMENT No. 2
(Units 6–9)
Total Marks: 100 Pass Marks: 40
Q.1 a) Suppose that four randomly chosen plots were treated with various level of
fertilizer resulting in the following yields of corn.
Fertilizer (kg/Acre) ( )
100 200 400 500
Production (Bushels/ Acre) ( )
70 72 80 100
(i) Estimate the linear regression of production on fertilizer .
(ii) Estimate the yield when no fertilizer is applied.
(iii) Estimate the yield when the average amount of fertilizer is applied.
(iv) Estimate how much yield is increased for every kilogram of fertilizer
Applied.
b. For 9 observations supply and price the following data was obtained
∑( ) ∑( ) ∑( )
∑( ) ∑( )( )
Obtain the estimated line of regression of on and estimate the supply
when the price is Rs. 125.
Q.2 a. Compute the correlation coefficient between the variables X and Y
represented in the following table:
i
x
2
4
5
6
8
11
i
y
18
12
10
8
7
5
Multiply each
i
x
value by 2 and add 6. Multiply each
i
y
value by 3 and subtract
15. Find the correlation co-efficient between the two new sets of values,
b. Explaining why you do or do not obtain the same result as above.
Q.3 a. Interpret the correlation coefficients, i.e. r = -1, r = 0, r= 1
b. What do you know about Correlation and Causation?
c. For a set of 50 pairs of observations, the standard deviations of and are
4.5 and 3.5 respectively. If the sum of products of deviations of and
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