PSY 215 Chapter 8

an extreme score- a single case (or a few cases) that stands out from the pack

outlier

The term ? describes the strength of an association between variables, and in correlations it is typically captured by a(n) ?. The precision of the correlation estimate is captured by a(n) ?

- effect size - r value - 95% CI

Mischel et al. (1972) studied delay of gratification in preschoolers. The researchers offered preschoolers a special reward if they could wait, or a less attractive treat if they chose not to wait. The researchers then conducted a follow-up study years later, studying the same preschoolers as adolescents. The researchers found a positive association between the preschoolers' waiting times and their self-control as adolescents. Match each question to the type of validity it interrogates. - construct validity - statistical validity - external validity - internal validity - is there a third variable that explains this relationship? - has this association been replicated? - can the results be generalized to all American children? - how well was delay of gratification measured?

- is there a third variable that explains this relationship? INTERNAL VALIDITY - has this association been replicated? STATISTICAL VALIDITY - can the results be generalized to all American children? EXTERNAL VALIDITY - how well was delay of gratification measured? CONSTRUCT VALDITY

A(n) ? is an extreme data point that can often inaccurately alter an effect size. ? occurs when all possible scores on a variable are not present, which can often inaccurately decrease an effect size. A(n) ? is when a set of data is not well represented by a straight line and can result in a zero effect size. All three of these issues can decrease ? validity.

- outlier - restriction of range - curvilinear relationship - statistical

An association claim with ? variables can be examined with a ? correlation, and the results of the test have two primary components. The first component tells you whether the association is positive or negative; it is referred to as ?. The second component tells you how closely the variables are associated; it is referred to as ?.

- two - bivariate - direction - strength

Leonor recently collected survey data and was curious about the association claim between gender and symptoms of mental illness. She found the following correlation between the two variables: r = −.47, 95% CI [−.59, −.35]. Identify the terms as either applicable or not applicable to this correlation. - negative - statistically significant - categorical - unusually large - not statistically significant - positive - moderate

applicable: - negative - statistically significant - categorical - unusually large not applicable: - not statistically significant - positive - moderate

Recently, researchers wanted to test the relationship between hours of exposure to violent video games and the number of real-life criminal behaviors. They found the following correlation between the two variables: r = .11, 95% CI [−.04, .26]. Identify the terms as either applicable or not applicable to this correlation. - not statistically significant - negative - moderate - statistically significant - positive - categorical - weak

applicable: - not statistically significant - positive - weak not applicable: - negative - moderate - statistically significant - categorical

Would a bar graph or a scatterplot be better to depict these results? do college students sleep fewer hours per day than high school students do?

bar graph

Would a bar graph or a scatterplot be better to depict these results? is job title linked to salary?

bar graph

Would a bar graph or a scatterplot be better to depict these results? is type of social media platform associated with feelings of jealously?

bar graph

an association that involves exactly 2 variables

bivariate correlation

Which two validities are the most important to establish for an association claim?

construct and statistical validity

José is investigating the relationship between exam anxiety and exam grades. He collects students' ratings of their own anxiety before an exam, and then he collects their exam scores afterward. When he calculates the correlation, he finds no relationship. José plots his data on this scatterplot and sees that both students who had no anxiety and students who had lots of anxiety performed poorly on exams—but students who reported moderate anxiety did very well. what issue is most likely affecting Jose's results?

curvilinear association

in which the relationship between 2 variables is not a straight line; it must be positive up to a point and then become negative

curvilinear association

Not knowing which variable came first

directionality problem

describes the strength or magnitude of a relationship between 2 or more variables

effect size

Professor Espejo wonders if there is an association between students' grades and extra credit points earned in his classes. He examines the number of extra credit points his students earned and the percentage grade his students earned without extra credit. He finds r = .28. Identify the true and false statements about Professor Espejo's study. professor Espejo's study involves one categorical and one quantitative variable

false

Professor Espejo wonders if there is an association between students' grades and extra credit points earned in his classes. He examines the number of extra credit points his students earned and the percentage grade his students earned without extra credit. He finds r = .28. Identify the true and false statements about Professor Espejo's study. this correlation tells him that students with lower grades are more likely than students with higher grades to earn extra credit points

false

true or false? a 95% CI gives you information about the strength of the association

false

true or false? a bivariate correlation can involve an association between 2 or more variables

false

true or false? bar graphs show the data points for each participant

false

true or false? scatterplots are often used to graph the relationship between a categorical variable and a quantitative variable

false

true or false? you can only examine correlations between 2 quantitative variables

false

Francisco is conducting an international study about a new website that is preparing to launch worldwide. He wants to see whether men or women are more likely to be interested in the new website so he can know which demographic to market it too. After he collects his data, Francisco discovers that whether the men and women surveyed were from Asia or North America changed how they responded to the website. Men from Asian countries were the most interested in his website, whereas women from North American countries were the least interested. Match each variable in Francisco's study to the correct definition. independent variable moderator dependent variable

independent variable- gender moderators- geographic area dependent variable- interest

Siva is investigating an association claim between political beliefs and age. His data show a correlation of r = .35. However, upon closer examination, Siva finds that the correlation is much stronger for men than it is for women. what type of variable is gender is this example?

moderator

a variable that, depending on its level, changes the relationship between 2 other variables

moderator

Pengyu is interested in the association between the height of professional basketball players and their free-throw percentage. She finds a statistically significant negative association in the entire last season of the NBA. Looking at her scatterplot, Pengyu finds that one player is much shorter and has a much better free-throw percentage than the rest of the players. She also finds that the negative association only exists for less experienced NBA players, not for more experienced NBA players. Identify the issues as either present or not present in Pengyu's study. - restriction of range - outlier - moderator - third variable problem

present: - moderator - outlier not present: - restriction of range - third variable problem

Sahil wants to investigate the relationship between reaction time and experience in tennis. He is considering different ways to operationalize tennis experience in his claim. Match each type of graph or data analysis method to the correct association claim. - scatterplot - correlation coefficient r - bar graph - magnitude of difference between means - reaction times are shorter in tennis experts than in non experts - reaction times decrease as the number of years playing tennis increases

reaction times are shorter in tennis experts than in non experts: -magnitude of difference between means - bar graph reaction times decrease as the number of years playing tennis increases: - scatterplot - correlation coefficient r

The process of conducting a study again to test whether the result is consistent

replication

if there is not a full range of scores on one of the variables in the association, it can make the correlation appear smaller than it really is

restriction of range

Would a bar graph or a scatterplot be better to depict these results? is age associated with number of hours of sleep?

scatterplot

Would a bar graph or a scatterplot be better to depict these results? is length of experience linked to salary?

scatterplot

Would a bar graph or a scatterplot be better to depict these results? is time spent using social media associated with feelings of jealously?

scatterplot

The bivariate correlation is there, but only because of some third variables

spurious association

A correlation that is unlikely to have come from a population in which the association is 0

statistically significant

Come up with an alternative explanation for the association between 2 variables, that alternative is some lurking third variable

third variable problem

Professor Espejo wonders if there is an association between students' grades and extra credit points earned in his classes. He examines the number of extra credit points his students earned and the percentage grade his students earned without extra credit. He finds r = .28. Identify the true and false statements about Professor Espejo's study. a scatterplot is the best way for professor Espejo to represent his results

true

Professor Espejo wonders if there is an association between students' grades and extra credit points earned in his classes. He examines the number of extra credit points his students earned and the percentage grade his students earned without extra credit. He finds r = .28. Identify the true and false statements about Professor Espejo's study. this correlation tells him that students with higher grades are more likely to earn extra credit points than students with lower grades are

true

true or false? a 95% CI gives you information about the precision of the association

true

true or false? a study with a small sample will have a wider 95% CI

true

true or false? an association claim is between measured variables

true

true or false? to understand a correlation, you must consider both its strength and its direction

true

true or false? when both variables in a study are measures, it is a correlational study

true

true or false? when one of the variables in an association is categorical, researchers often analyze the difference between the means of the groups

true

true or false? you can infer statistical significance from a 95% CI

true