Sample question: Given a set of data with sample size 8 and r = 0.454, find the linear regression test value.
Note: r is the correlation coefficient.
Step 1: Find r, the correlation coefficient, unless it has already been given to you in the question. In this case, r is given (r = .0454). Not sure how to find r? See: Correlation Coefficient for steps on how to find r.
Step 2: Use the following formula to compute the test value (n is the sample size):

How to solve the formula:
- Replace the variables with your numbers:
T = .454√((8 – 2)/(1-[.454]2 ))- Subtract 2 from n:
8 – 2 = 6 - Square r:
.454 × .454 = .206116 - Subtract step (3) from 1:
1 – .206116 = .793884 - Divide step (2) by step (4):
6 / .793884 = 7.557779 - Take the square root of step (5):
√7.557779 = 2.74914154 - Multiply r by step (6):
.454 × 2.74914154 = 1.24811026
- Subtract 2 from n:
The Linear Regression Test value, T = 1.24811026
That’s it!