Hypotheses and Research Questions Predicting functional relationships between variables

Definition: A hypothesis is a tentative prediction about the nature of the relationship between two or more variables. –A hypothesis represents an educated guess about what will happen in an experiment –Hypotheses are always held tentatively A research question is simply a hypothesis stated in question form.

Should I use a hypothesis or a research question? Research Questions –Useful if there is little previous research on the topic –Allows a researcher to conduct more open- ended inquiries. –A wider range of outcomes can be reported –May encourage excessive manipulation of findings or “fishing expeditions.” Hypotheses –Useful if there is an established line of research –Useful if a likely outcome can be anticipated in advance –Useful to test a specific theory or model –Can inhibit flexibility or blind a researcher to unanticipated results

Types of Hypotheses Null hypothesis Symbol = H o or H0 Experimental hypothesis Symbol = H 1, H a, etc. nondirectional (two-way) directional (one-way) Research Question Symbol = RQ or R

Null Hypothesis the null hypothesis is a statistical hypothesis, used to determine whether the results of an experiment are statistically significant. It posits that there is “no relationship” between two variables, or “no difference” between two groups. The null hypothesis is “supported,” if the results are statistically non-significant –the null hypothesis is never “proven” (at least not by a single study) –impossibility of proving a negative The null hypothesis is “rejected,” in favor of the experimental hypothesis, if the results are statistically significant

Experimental hypothesis A prediction that there will be statistically significant findings –significant differences or correlations between groups or among variables Nondirectional hypothesis –significant difference in any direction Directional hypothesis –Predicts that a specific group or condition will be higher or have more of something, or –predicts the specific direction that a correlation will take (positive negative, curvilinear)

Examples Null hypothesis: –H o : High exposure to violent video games does not produce more antisocial behavior in elementary school children than low exposure. Non directional hypothesis: –H 1 : Japanese and American supervisors will differ significantly in their use of threats as a compliance gaining strategy. Directional hypothesis –H a : Deaf children whose parents are deaf will acquire language faster than deaf children whose parents are not deaf.

Phrasing hypotheses and research questions Avoid vague or nebulous wording –the hypothesis or research question must be clear and concise –The hypothesis or research question must be testable. –The hypothesis or research question must be falsifiable. –Wrong: Do students with high GPAs feel better about themselves than students with low GPAs? –Right: Do undergraduates with GPAs greater than 3.0 have higher self esteem than undergraduates with GPAs of lower than 2.0?

Identify each of the following: There are significantly more Republicans than Democrats among registered voters earning $100,000 or more per year. There is no correlation between college GPA and employees’ salaries 5 years post graduation. Does frequency of church attendance predict marital fidelity? Repeated head trauma caused by participation in children’s sports has a significant effect on children’s critical thinking skills. Experienced elementary teachers will display less negative attitudes toward stutterers than inexperienced teachers.