CA Foundation · Quantitative Aptitude · Correlation and Regression
Ten trainee analysts are ranked by two examiners with no ties, and Spearman's rank correlation is found to be 0.6. What is the sum of squared rank differences, Σd²?
Σd² is 66. With n = 10 the denominator n(n²−1) is 990. Setting 1 − 6Σd²/990 = 0.6 gives 6Σd²/990 = 0.4, so Σd² = 66. Other values do not reproduce r = 0.6 under the formula.
- A40
- B33
- C66Correct
- D99
Explanation
0.6 = 1 − 6Σd²/(10×99), so 6Σd²/990 = 0.4. Then Σd² = 0.4×990/6 = 66. Choosing 99 comes from dividing by 4 instead of 6, which is a wrong rearrangement.
Did you get it right without looking?
One question tells you little. A timed set on Correlation and Regression shows your real accuracy, how long you take and where you lose marks.
More Correlation and Regression questions
- A scatter diagram of daily temperature (X) and sales of woollen jackets (Y) for a Ludhiana retailer shows points falling from upper left to …
- Two variables X and Y have standard deviations 3 and 4 respectively, and the correlation coefficient between them is 0.5. What is the varian…
- A study finds that the number of ice creams sold in a city and the number of drowning incidents are strongly positively correlated across th…
- Which of the following statements about Karl Pearson's coefficient of correlation (r) is correct?
- Let u = (x - 10)/5 and v = (30 - y)/2. For the data, r(u, v) = 0.6, σu = 2 and σv = 3. What is the regression coefficient of y on x (b_yx)?
- An analyst studies 17 yearly observations of the price of a commodity and its demand. Only 2 pairs of deviations are concurrent, that is, th…