Research Methods / Stats Prpjet Quizes Flashcards
Psychology 101 students are assigned ranks based on their total scores on a 50-item midterm exam. The ranks represent a(n) \_\_\_\_\_ scale of measurement. A. nominal B. interval C. ratio D. ordinal
Answer D is correct. Ranks are a type of ordinal score – i.e., when scores are reported as ranks, it’s possible to conclude that one rank is higher or lower than another but it’s not possible to conclude that the differences between adjacent ranks are equal. For example, if students with the three highest midterm scores obtained scores of 50, 49, and 45, the student who received the score of 50 would be assigned a rank of 1, the student who received the score of 49 would be assigned a rank of 2, and the student who received the score of 45 would be assigned a rank of 3. In this situation, there’s only a one point score difference between the ranks of 1 and 2 but a four point score difference between the ranks of 2 and 3.
The mode, median, and mean for a distribution of final exam scores are 75, 50, and 35, respectively. Based on this information, you can conclude that this distribution is: A. positively skewed. B. negatively skewed. C. leptokurtic. D. platykurtic.
Answer B is correct. When the mode (the most frequent score) has the highest value and the mean (the arithmetic average) has the lowest value, this means that most scores are “piled up” in the positive side of the distribution and only a relatively few scores are in the negative tail. When this occurs, the distribution is negatively skewed.
A school psychologist designs a study to determine if student gender and grade level are related to the number of interactions male and female teachers have with their students. This study has \_\_\_ independent variables and \_\_\_ dependent variable(s). A. 2; 1 B. 2; 2 C. 3; 1 D. 3; 2
Answer C is correct. If you’re having trouble distinguishing between a study’s independent and dependent variables, remember that the independent variable is believed to have an effect on the dependent variable and that, for questions like this one, anything that varies will be either an independent or dependent variable. Converting the information given in the description of the study to the following question might be helpful: “What are the effects of the [independent variable(s)] on the [dependent variable(s)]?” For this study, the question is, “What are the effects of the student gender, student grade level, and teacher gender on number of teacher-student interactions? In other words, this study has three independent variables (student gender, student grade level, and teacher gender) and one dependent variable (number of teacher-student interactions).
A distribution of scores has a mean of 60 and standard deviation of 5 and scores are normally distributed. Based on this information, you can conclude that about \_\_\_% of scores fall between the scores of 50 and 70. A. 50 B. 68 C. 95 D. 99
Answer C is correct. In this distribution, the scores of 50 and 70 are minus and plus two standard deviations from the mean. In a normal distribution, about 95% of scores fall between the scores that are minus and plus two standard deviations from the mean.
A sociologist proposes that the reason why people living below the poverty level have worse outcomes even for relatively minor health problems is because they have little or no access to adequate healthcare. In this situation, lack of access to healthcare is a(n) \_\_\_\_\_\_\_\_\_\_ variable. A. moderator B. mediator C. control D. outcome
Answer B is correct. Mediator variables explain the relationship between independent and dependent variables. In the situation described in this question, the psychologist believes that lack of access to adequate healthcare explains the relationship between poverty and health outcomes.
The Solomon four-group design is used to:
A. evaluate the effects of pretesting.
B. reduce the effects of multiple treatment interference.
C. ensure that groups are similar at the beginning of the study.
D. reduce experimenter expectancy effects.
Answer A is correct. The Solomon four-group design is used to identify the effects of pretesting on a study’s internal and external validity.
A researcher conducted a study to assess the effects of cognitive behavior therapy for treating depression in adolescents by comparing it to nondirective supportive therapy. Fifty adolescents who recently received a diagnosis of major depressive disorder were randomly assigned to one of the two therapies. Each participant’s level of depression was assessed at the beginning of treatment and one month after treatment ended. The results indicated that adolescents in both groups improved to the same degree in terms of depressive symptoms. Which of the following is the biggest threat to this study’s internal validity? A. differential selection B. reactivity C. maturation D. instrumentation
Answer C is correct. The lack of difference in the outcomes for the two groups in this study could be due to the fact that the treatments were equally effective or to maturation since symptoms of major depressive disorder tend to decline in severity or remit over time with or without treatment.
The best way to reduce the effects of differential selection on the results of a research study is to:
A. randomly select subjects from the population.
B. randomly assign subjects to the treatment groups.
C. use the single-blind technique.
D. use the double-blind technique.
Answer B is correct. Differential selection occurs when subjects in different groups differ at the beginning of a study in a way that affects the results of the study, and this difference is due to the way that subjects were assigned to the groups. The best way to control differential selection is to randomly assign subjects to groups, which helps ensure that subjects in the different groups are similar at the beginning of the study.
Counterbalancing is most useful for controlling which of the following threats to external validity? A. reactivity B. selection-treatment interaction C. multiple treatment interference D. pretest sensitization
Answer C is correct. Counterbalancing is used to control multiple treatment interference, which may occur whenever each participant receives multiple levels of the independent variable. It involves administering the levels in a different order to different groups of subjects.
To evaluate a brief intervention for improving the social skills of adolescents with autism spectrum disorder, a researcher administers a measure of social skills to a sample of adolescents with this diagnosis, chooses the adolescents with the lowest scores on this measure to participate in the intervention, and then re-administers the measure of social skills one week after the adolescents have participated in the intervention. The biggest threat to the internal validity of this study is: A. instrumentation. B. reactivity. C. pretest sensitization. D. statistical regression.
Answer D is correct. Statistical regression threatens a study’s internal validity whenever subjects are chosen because of their extreme scores on a pretest. Because this study included only adolescents with the lowest scores on the measure of social skills, their scores on the posttest measure of social skills are likely to improve somewhat just because of statistical regression.
An advantage of the multiple baseline across behaviors design over the ABAB design is that it:
A. helps the researcher determine if there’s a causal relationship between the independent and dependent variables.
B. doesn’t require the researcher to withdraw a treatment from a behavior during the course of the study once it’s been applied to that behavior.
C. allows the researcher to compare the effectiveness of two different treatments during the course of the study.
D. doesn’t require the behavior to exhibit a stable pattern during the baseline phase before the treatment is applied to that behavior.
Answer B is correct. The multiple-baseline across behaviors design involves sequentially applying a treatment to two or more behaviors. An advantage of this design is that, once the treatment has been applied to a behavior, it continues being applied to that behavior for the duration of the study.
A psychologist conducts a study to evaluate the effects of type of workshop (face-to-face and online) and level of motivation (high, average, and low) on mock EPPP scores. The results indicate that there are statistically significant main effects of both independent variables and a statistically significant interaction. When interpreting these results, the psychologist will conclude which of the following?
A. Both types of workshop are effective regardless of a person’s level of motivation.
B. Both types of workshop are ineffective regardless of a person’s level of motivation.
C. The most effective type of workshop is the same regardless of a person’s level of motivation.
D. The most effective type of workshop depends on the person’s level of motivation.
Answer D is correct. The interaction between type of workshop and motivation is statistically significant, which means that the effects of type of workshop differ for different levels of motivation. For example, the face-to-face workshop might be more effective for people with low motivation, while the online workshop is more effective for people with moderate or high motivation.
Like the AB single-subject design, the \_\_\_\_\_\_\_\_\_\_ group design involves measuring the dependent variable measure multiple times before and after applying the independent variable. A. Solomon four-group B. factorial C. counterbalanced D. time-series
Answer D is correct. The AB single-subject design has a single baseline (no treatment) phase that is followed by a single treatment phase. Like the time-series group design, it involves measuring the dependent variable multiple times before and after the independent variable (treatment) is applied.
To obtain a sample for her study, a researcher randomly selects 25 schools from the 90 schools in a single school district and then interviews all teachers in each selected school. The researcher has used which of the following sampling methods? A. stratified sampling B. cluster sampling C. systematic sampling D. convenience sampling
Answer B is correct. Cluster sampling involves randomly selecting a sample of clusters from all of the clusters in the designated population (e.g., schools in a school district) and then either including in the study all individuals in each selected cluster or a random sample of individuals in each selected cluster.
The primary characteristic that distinguishes true experimental research from quasi-experimental research is that, when conducting a true experimental research study, the researcher is able to:
A. randomly select subjects from the population.
B. randomly assign subjects to different treatment groups.
C. use a parametric statistical test to analyze the data.
D. use a nonparametric statistical test to analyze the data.
Answer B is correct. True experimental research allows researchers to control many aspects of their studies, which allows them to determine if observed changes in the dependent variable were caused by the independent variable. The most important aspect of this control is the ability to randomly assign subjects to different treatment groups, which helps ensure that groups are equivalent at the beginning of the study. (The appropriate use of a parametric or nonparametric statistical test depends primarily on the type of data that is to be analyzed, not whether the study was true or quasi-experimental.)
