Psych M&S Exam 3

parametric tests

relatively powerful significance test that uses estimations of population parameters in which the data must satisfy certain assumptions

non-parametric tests

a test in which the distribution of results does not need to meet a certain required assumptions to be analyzed

types of non-parametric tests

• mann-whitney u test

• wilcoxon t test

effect size

similar to the correlation coefficient and tells information about the magnitude of two groups and is specifically measured by cohen’s d

related t test

compares the means of two measurements taken from the same individual, object, or related units

repeated measures design

testing the same subjects under two or more conditions or over two or more time periods

paired samples t test

compares the means of two measurements taken from the same individual, object or group

data assumptions (related)

assumption that participants related at pretest are the same at posttest

difference mean

the mean of differences between pairs of scores in a related design

independent variable

grouping variable - ex: genre of music

dependent variable

variable of outcome - ex: what do we want to compare

null hypothesis

assumes there is no significant difference between the means of the two groups being compared

null hypothesis of a paired samples t test

the mean difference between the paired observations is zero

null hypothesis of an independent samples t test

the mean of group A is equal to the mean of group B

alternative hypothesis

proposes a specific relationship or different between the groups or variables being studied

alternative hypothesis of a paired samples t test

the mean difference between the paired observations is not zero

alternative hypothesis of an independent samples t test

the mean of group A is not equal to the mean of group B

unrelated t test

data that comes from two entirely different groups of people

independent samples design

samples are divided into two groups

data assumptions (unrelated)

assumption that participants of 1st group are different from the participants of 2nd group

children in two English classes have been recruited for a research study. one class has undergone an experimental teaching method designed to improve spelling. both groups undergo a spelling test at the end of the experimental program. the data met parametric requirements, so the most suitable difference test is

an unrelated t test

in a related t test, the difference mean is

mean of differences between pairs of scores n a related design

the null hypothesis of an independent-samples t test states

the means of the two populations are the same

an unrelated t test is also referred to as

independent samples t test

a related t test is also referred to as

paired samples t test

participants with mild to moderate depression are given a new type of cognitive-behavioral therapy. their depression levels are measures using a standardized scale before the therapy begins and then again after the therapy has concluded, typically after several weeks. the alternative hypothesis would state

depression levels will be significantly lower after therapy compared when therapy began

participants’ mood states are measured before and after a 30-minture aerobic exercise session using a mood inventory scale. the null hypothesis would state

aerobic exercise will not significantly improve participants’ mood states

what is an effect size in the context of psychological research?

a statistical calculation that describes the magnitude of the difference between two groups

researchers want to examine if there is a difference in GPA among biology majors and psychology majors. upon reviewing their data, the researchers discovered that their data does not follow a normal distribution. which non-parametric test would researchers use?

mann-whitney U test

participants are randomly assigned to one of two groups. one group performs a set of cognitive tests where rock music is played, while the other performs the same tasks in a room where classical music is played. performance on a memory task is measured and compared between the two groups. what is the independent variable?

genre of music. participants listened to either rock music or classical music

participants are randomly assigned to one of two groups. one group performs a set of cognitive tests where rock music is played, while the other performs the same tasks in a room where classical music is played. performance on a memory task is measured and compared between the two groups. what are the levels of the independent variable?

level 1: participants who listened to rock music

level 2: participants who listened to classical music

participants are randomly assigned to one of two groups. one group performs a set of cognitive tests where rock music is played, while the other performs the same tasks in a room where classical music is played. performance on a memory task is measured and compared between the two groups. what is the dependent variable?

performance on the memory task