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# 12 the diagrammatic representation of two variables

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Unformatted text preview: is uniformity in the performance of students in the two tests. Exercise – 8 I. Choose the correct answer: 1.Limits for correlation coefficient. (a) –1 ≤ r ≤ 1 (b) 0 ≤ r ≤ 1 (c) –1 ≤ r ≤ 0 (d) 1 ≤ r ≤ 2 2. The coefficient of correlation. (a) cannot be negative (b) cannot be positive (c) always positive (d)can either be positive or negative 3. The product moment correlation coefficient is obtained by ΣXY ΣXY (a) r = (b) r = xy n σx σy ΣXY (d) none of these n σx 4. If cov(x,y) = 0 then (a) x and y are correlated (b) x and y are uncorrelated (c) none (d) x and y are linearly related (c) r = 211 5. If r = 0 the cov (x,y) is (a) 0 (b) -1 (c) 1 (d) 0.2 6. Rank correlation coefficient is given by 6ΣD 2 6ΣD 2 6ΣD 2 (a) 1 + 3 (b) 1 − 2 (c) 1 − 3 n −n n −n n −n 2 6Σ D (d) 1 − 3 n +n 7. If cov (x,y) = σx σy then (a) r = +1 (b) r = 0 (c) r = 2 (d) r = -1 8. If D2 = 0 rank correlation is (a) 0 (b) 1 (c)0.5 (d) -1 9. Correlation coefficient is independent of change of (a) Origin (b) Scale (c) Origin and Scale (d) None 10. Rank Correlation was found by (a) Pearson (b) Spearman (c) Galton (d) Fisher II. Fill in the blanks: 11 Correlation coefficient is free from _________. 12 The diagrammatic representation of two variables is called _________ 13 The relationship between three or more variables is studied with the help of _________ correlation. 14 Product moment correlation was found by _________ 15 When r = +1, there is _________ correlation. 16 If rxy = ryx, correlation between x and y is _________ 17 Rank Correlation is useful to study ______characteristics. 18 The nature of correlation for shoe size and IQ is _________ III. Answer the following : 19 What is correlation? 20 Distinguish between positive and negative correlation. 21 Define Karl Pearson’ s coefficient of correlation. Interpret r, when r = 1, -1 and 0. 22 What is a scatter diagram? How is it useful in the study of Correlation? 212 23 24 25 26 27 28 29 30 31 32 33 Distinguish between linea...
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