Procedure Used to Test for Significance

Whenever we perform a significance test, it involves comparing a test value that we have calculated to some critical value for the statistic. It doesn't matter what type of statistic we are calculating (e.g., a t-statistic, a chi-square statistic, an F-statistic, etc.), the procedure to test for significance is the same.
1. Decide on the critical alpha level you will use (i.e., the error rate you are willing to accept).
2. Conduct the research.
3. Calculate the statistic.
4. Compare the statistic to a critical value obtained from a table.
If your statistic is higher than the critical value from the table:
· Your finding is significant.
· You reject the null hypothesis.
· The probability is small that the difference or relationship happened by chance.
If your statistic is lower than the critical value from the table:
· Your finding is not significant.
· You fail to reject the null hypothesis.
· The probability is high that the difference or relationship happened by chance.

 

Pearson Product-Moment Correlation Coefficient

Table of Critical Values

df= N-2

N = number of pairs of data
Level of significance for two-tailed test
.10 .05 .02 .01
1 .988 .997 .9995 .9999
2 .900 .950 .980 .990
3 .805 .878 .934 .959
4 .729 .811 .882 .917
5 .669 .754 .833 .874
6 .622 .707 .789 .834
7 .582 .666 .750 .798
8 .549 .632 .716 .765
9 .521 .602 .685 .735
10 .497 .576 .658 .708
11 .476 .553 .634 .684
12 .458 .532 .612 .661
13 .441 .514 .592 .641
14 .426 .497 .574 .628
15 .412 .482 .558 .606
16 .400 .468 .542 .590
17 .389 .456 .528 .575
18 .378 .444 .516 .561
19 .369 .433 .503 .549
20 .360 .423 .492 .537
21 .352 .413 .482 .526
22 .344 .404 .472 .515
23 .337 .396 .462 .505
24 .330 .388 .453 .495
25 .323 .381 .445 .487
26 .317 .374 .437 .479
27 .311 .367 .430 .471
28 .306 .361 .423 .463
29 .301 .355 .416 .456
30 .296 .349 .409 .449
35 .275 .325 .381 .418
40 .257 .304 .358 .393
45 .243 .288 .338 .372
50 .231 .273 .322 .354
60 .211 .250 .295 .325
70 .195 .232 .274 .302
80 .183 .217 .256 .284
90 .173 .205 .242 .267
100 .164 .195 .230 .254