Types of Variables and Data Flashcards
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.
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).
