Advertisements
Advertisements
Question
Values of two regression coefficients between the variables X and Y are `b_"yx" = - 0.4` and `b_"xy"` = - 2.025 respectively. Obtain the value of correlation coefficient.
Solution
Correlation coefficient is
`r = ±sqrt(b_"yx".b_"xy")`
`r = ±sqrt(-2.025 xx - 0.4)`
`r = ±sqrt(0.81)`
⇒ r = -0.9 (∵ `b_"yx" and b_"xy"` are negative)
APPEARS IN
RELATED QUESTIONS
Bring out the inconsistency; if any: byx + bxy = 1.30. and r = 0.75
Two samples from bivariate populations have 15 observations each. The sample mean of X and Y are 25 and 18 respectively. The corresponding sum of squares of deviations from means are 136 and 148. The sum of product of deviations from respective means is 122. Obtain the equation of line of regression of X on Y.
For 50 students of a class, the regression equation of marks in statistics (X) on the marks in accountancy (Y) is 3y – 5x + 180 = 0. The mean marks in accountancy is 44 and the variance of marks in statistics is `(9/16)^(th)` of the variance of marks in accountancy. Find the mean marks in statistics and the correlation coefficient between marks in the two subjects.
Bring out the inconsistency, if any in the following :
bYX = bXY = 1.50 and r = -0.9
Bring out the inconsistency, if any in the following :
bYX = 2.6 and bXY = `1/2.6`
For a bivariate data,
`bar x = 53 , bar y = 28 , "b"_"xy" = -1.5 and "b"_"xy"=- 0.2` Find
Correlation coefficient between X and Y
For a bivariate data,
`bar x = 53 , bar y = 28 , "b"_"xy" = - 0.2` , `"b"_"yx" = -1.5` Find
Estimate of Y , When X = 50.
For a bivariate data,
`bar x = 53 , bar y = 28 , "b"_"yx"=-1.5 and "b"_"xy"=- 0.2` Find Estimate of X for y = 25.
For the two regression equations 4y = 9x + 15 and 25x = 6y + 7 find correlation coefficient r, `barx, bary`
By using the data `bar"x"` = 25 , `bar"y" = 30 ; "b"_"yx" = 1.6` and `"b"_"xy" = 0.4` find,
(a) The regression equation y on x.
(b) What is the most likely value of y when x = 60?
(c) What is the coefficient of correlation between x and y?
Find the line of best fit for the following data, treating x as the dependent variable (Regression equation x on y):
| X | 14 | 12 | 13 | 14 | 16 | 10 | 13 | 12 |
| Y | 14 | 23 | 17 | 24 | 18 | 25 | 23 | 24 |
Hence, estimate the value of x when y = 16.
The coefficient of correlation between the values denoted by X and Y is 0.5. The mean of X is 3 and that of Y is 5. Their standard deviations are 5 and 4 respectively.
Find:
(i) the two lines of regression.
(ii) the expected value of Y, when X is given 14.
(iii) the expected value of X, when Y is given 9.
Calculate Karl Pearson’s coefficient of correlation between x and y for the following data and interpret the result:
(1, 6), (2, 5), (3, 7), (4, 9), (5, 8), (6, 10), (7, 11), (8, 13), (9, 12)
The marks obtained by 10 candidates in English and Mathematics are given below:
| Marks in English | 20 | 13 | 18 | 21 | 11 | 12 | 17 | 14 | 19 | 15 |
| Marks in Mathematics | 17 | 12 | 23 | 25 | 14 | 8 | 19 | 21 | 22 | 19 |
Estimate the probable score for Mathematics if the marks obtained in English are 24.
For 5 observations of pairs (x, y) of variables X and Y, the following results are obtained:
∑x = 15, ∑y = 25, ∑x2 = 55, ∑y2 = 135, ∑xy = 83.
Calculate the value of bxy and byx.
If the two regression coefficients are 0.8 and 0.2, then the value of coefficient of correlation r will be ______.
The following table shows the Mean, the Standard Deviation and the coefficient of correlation of two variables x and y.
| Series | x | y |
| Mean | 8 | 6 |
| Standard deviation | 12 | 4 |
| Coefficient of correlation | 0.6 | |
Calculate:
- the regression coefficient bxy and byx
- the probable value of y when x = 20
If the correlation coefficient of two sets of variables (X, Y) is `(-3)/4`, which one of the following statements is true for the same set of variables?
