CA Foundation P3 · Chapter 17 · Question 7 of 9
The coefficient of correlation from 25 pairs of observations is 0.8. Taking PE = 0.6745 x (1 − r²)/√n, the probable error of r is (to four decimals):
Test yourself: pick an answer
Reveal answer & explanation
Correct answer: B) 0.0486
Explanation
PE = 0.6745 x (1 − r²)/√n = 0.6745 x (1 − 0.64)/5 = 0.6745 x 0.072 = 0.0486. 0.0720 is the standard error (without 0.6745), 0.0270 uses (1 − r) instead of (1 − r²), and 0.2428 forgets to divide by √n.
More Correlation and Regression MCQs
- Q9When the coefficient of correlation r = 0, the two lines of regression are:
- Q1The coefficient of correlation r always lies between:
- Q2If Cov(x, y) = 18, σx = 4 and σy = 6, the coefficient of correlation is:
- Q3The two regression coefficients are byx = 0.8 and bxy = 0.45. The coefficient of correlation is:
- Q4For 6 pairs of ranks, the sum of squares of rank differences Σd² = 14. Spearman's rank correlation coefficient is (to two decimals):