This state was the first to establish a merit based civil service system

In order to study causal relationships,

A) the null hypothesis must not be rejected. B) external validity is essential. C) we must use a t-test or F-test. D) there must be variation of the independent variable.

Without ________, there would be no differences between groups to test

A) nonmanipulated independent variables B) degrees of freedom C) uniformity D) variation