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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
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32
33 Distinguish between linea...
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 Winter '08
 Moshiri
 Business

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