PSY 3211 CHAPTER 7

nondirectional hypothesis

Predicts the existence of a relationship, not its direction

Directional hypothesis (one-tailed)

States the kind of relationship between two conditions. E.g. People who do homework without the TV on produce better results than those who do homework with the TV on.

research hypothesis

The hypothesis that the variables under investigation are related in the population - that the observed effect based on sample data is true in the population. Whereas a null hypothesis is a statement of no relationship between variables, a research hypothesis is a definite statement that a relationship exists between variables. For example, for each of the null hypotheses stated earlier, here is a corresponding research hypothesis. Notice that we said "a" and not "the" corresponding research hypothesis because there certainly could be more than one research hypothesis for any one null hypothesis. The Research Hypothesis The average score of 9th graders is dif erent from the average score of 12th graders on the ABC memory test. The effectiveness of community-based, long-term care is dif erent from the effectiveness of in-home, longterm care in promoting the social activity of older adults when measured using the Margolis Scale of Social Activities. Slower reaction time and problem-solving ability are positively related.

null hypothesis

the hypothesis that there is no significant difference between specified populations, any observed difference being due to sampling or experimental error. ESSENTIALLY, What are the basic purposes of the null hypothesis? The null hypothesis acts as both a starting point and a benchmark against which the actual outcomes of a study can be measured. Let's examine each of these purposes in more detail. First, the null hypothesis acts as a starting point because it is the state of affairs that is accepted as true in the absence of any other information.