RESEARCH METHODOLOGY

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STATISTICAL TECHNIQUES AND TOOLS

REGRESSION

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Which of the following can affect the value of the correlation r? I. A change in measurement units II. Adding a constant to all values of the y-variable III. Interchanging x and y IV. Adding another data point
A
III only
B
IV only
C
III and IV
D
II, III, and IV
Explanation: 

Detailed explanation-1: -Since the formula for calculating the correlation coefficient standardizes the variables, changes in scale or units of measurement will not affect its value.

Detailed explanation-2: -The closer all of the data points are to the line, in other words the less scatter, the higher the degree of correlation. The scatterplots presented below perhaps best illustrate how the correlation coefficient changes as the linear relationship between the two variables is altered.

Detailed explanation-3: -The correlation coefficient r ranges between-1 and +1. A positive r values indicates that as one variable increases so does the other, and an r of +1 indicates that knowing the value of one variable allows perfect prediction of the other.

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