Evidence-Based Practice for Nurses

value “C.” How would the decision about the null hypothesis be affected by
either of these two alphas? If the alpha level is set at .05, the critical point
would be significant and the null hypothesis would be rejected. However, if
an alpha level of .01 is selected, the critical point would be nonsignificant,
and the researcher would accept the null hypothesis. To avoid any temptation
to select alpha levels that bias decision making, researchers must always state
their selected alpha levels in the initial research proposal. Strong rationales
for the one selected must also be provided.

13.8 Using Statistical Tests

to Make Inferences About

Populations

1. When a researcher accepts the null hypothesis when it really should have been rejected,
   the researcher: (Select all that apply.)
   a. committed a type I error.
   b. committed a type II error.
   c. obtained significant results.
   d. obtained nonsignificant results.


2. The most commonly used alpha level in nursing research is
   a. .001.
   b. .0001.
   c. .005.
   d. .05.

TEST YOUR KNOWLEDGE 13-7

How did you do? 1. b, d; 2. d

At the end of this section, you will be able to:

‹Match common notations with associated statistical tests

‹Identify common statistical tests as parametric or nonparametric

‹Describe tests used to determine statistically significant differences between

groups

‹Discuss tests used to determine statistically significant differences among

variables

‹Assign commonly used statistical tests to examples based on type of research

question and level of measurement

13.8 Using Statistical Tests to Make Inferences About Populations 361