These tests on site have reached good values when it comes to their statistical properties.
To measure this, the coefficient of reliability, the Cronbach’s Alpha is involved. Cronbach’s Alpha measures how close the questions in a test/questionaire are related to each other as a group.
This measurement can be expressed into a scale, that goes from 0 to 1.
The scale for ex. the Coefficient Cronbach’s Alpha appears below:
0.0 —> 0.50 = Unacceptable
0.50 —> 0.60 = Poor
0.61 —> 0.70 = Questionable
0.71 —> 0.80 = Acceptable
0.81 —> 0.89 = Good
0.90 —> 1.00 = Excellent
Given the alpha values of the tests appearent on site, one sees by comparison that those reflect acceptable – to good alpha values. Which, in turn, reflects a high level internal consistency.
Thus, these tests are reliable.
Below you can find the norms from each of the tests: