Identifying IV and DV Variables and Hypotheses
For the three linked studies you were asked to address the questions directly below those studies. The questions and studies are repeated here for convenience. Answers appear below.
(a) Humor and Psychology
1. What hypotheses do the authors present?
2. Is this first hypothesis is directional, non-directional, or null?
3. What are the IV and DVs in the first hypothesis?
(b) Computer Assisted Instruction
4. What is the hypothesis in this study?
5. Is this hypothesis directional, non-directional, or null?
6. What are the IV and DVs in these hypotheses?
7. What scale of measurement is the IV?
(c) Blood Pressure and Stereotype Threat
8. What is the hypothesis for this study?
9. What are the variables in this hypothesis, and which are IV and DV?
Answers
(a) Humor and Psychology
1. What hypotheses do the authors present?
The author presents three general hypotheses on page 49 of the report (page 4 of the PDF). The first is worded as follows:
“First, I suggest that one’s sense of humor and PsyCap are positively and significantly related (Hypothesis 1).”
2. Is this first hypothesis is directional, non-directional, or null?
3. What are the IV and DVs in the first hypothesis?
This is a directional hypothesis.
IV and DV: Not clear which is IV and DV, not altogether clear in article lit. review which is IV or DV, although it seems sense of humor may be the IV according to the lit. review provided. Note that PsyCap is a composite score and variable, and there are also four distinct sub-scores that produce distinct sub-variables (Hope, Confidence, Optimism, and Resiliency)
Note: It is awkward to use the term “significant” or “significantly” in a hypothesis. The term significant has special meaning in research, especially statistics: significant means that one has rejected a null hypothesis. We’ll cover this meaning in more detail when we review inferential statistics. When researchers declare results, not hypotheses, to be statistically significant, they are stating that the null has been rejected. Thus, the word significant reflects an action or decision one makes about a null hypothesis, and it does not have meaning beyond this specific decision. Many authors confuse this point and erroneously include “significant” in the wording of a hypothesis -- don’t make this mistake. Rather, simply state the nature of the relationship you expect between variables observed.
(b) Computer Assisted Instruction
4. What is the hypothesis in this study?
The last sentence immediately before the Method section is the hypothesis. He writes (page 3 of the PDF document):
“Based on this research review, it is anticipated in this study that students who receive TI plus CAI would perform better than those who receive only TI.”
5. Is this hypothesis directional, non-directional, or null?
6. What are the IV and DVs in these hypotheses?
7. What scale of measurement is the IV?
Hypothesis is directional.
IV = type of instruction (TI + CAI vs. TI only) and the DV = student performance (computer science achievement test)
IV is nominal
(c) Blood Pressure and Stereotype Threat
8. What is the hypothesis for this study?
They write (on page 1 of the PDF document):
“We hypothesized an interaction between stereotype threat and race such that when stereotype threat was relatively high, African Americans would have higher blood pressure levels than European Americans, but when stereotype threat was low, no racial differences would occur.”
9. What are the variables in this hypothesis, and which are IV and DV?
The variables are stereotype threat (high and low), race (Black and White), and blood pressure. The IV are race and stereotype threat, the DV is blood pressure.