PSY 290-Chapter 8
Why would a single outlier be a problem?
As it turns out, adding that one data point changes the correlation depicted in the scatterplot from r = .26 to r = .37! Depending on where the outlier is, it can make a medium-sized correlation appear stronger, or a strong correlation appear weaker, than it really is
causal claim
Association claims involve two variables, both of which are measured in a set of participants. (If either of the variables is manipulated, the study is an experiment, which could potentially test a _______.)
correlational
It's important to remember that no matter what kind of graph you make, no matter what kind of statistic you use, when both variables are measured, the study is _______, and therefore it can support an association claim.
bivariate correlation
, or bivariate association, is an association that involves exactly two variables.
Temporal precedence
. The causal variable must precede the effect variable; it must come first in time.
mediator
A _____ variable is the variable that causes mediation in the dependent and the independent variables. In other words, it explains the relationship between the dependent variable and the independent variable. (e.g. explains the relationship)
effect size
All associations are not equal; some are stronger than others. the ______________ describes the strength of an association.
outlier
An ______ is an extreme score—a single case (or sometimes a few) that stands out far away from the pack. Depending on where it sits in relation to the rest of the sample, a single ______ can have a strong effect on the correlation coefficient r.
the third-variable problem
The internal validity criterion is often called ___________: When we can come up with an alternative explanation for the association between two variables, that alternative explanation is the third variable.
third-variable problem
The internal validity criterion is often called the ________: When we can come up with an alternative explanation for the association between two variables, that alternative explanation is the third variable
directionality problem
The temporal precedence criterion is sometimes called the __________, because we don't know which variable came first
directionality problem
The temporal precedence criterion is sometimes called the _____________, because we don't know which variable came first
Covariance of cause and effect
There must be correlation, or association, between the cause variable and the effect variable.
Internal validity.
There must be no plausible alternative explanations for the relationship between the two variables.
associations
To investigate ______, researchers need to measure the first variable and then measure the second variable—in the same group of people. Then they use graphs and simple statistics to describe the type of relationship between the variables.
statistics/R/ t test
When at least one of the variables in an association claim is categorical, as in the online dating example, researchers may use different ___________ to analyze the data. Although they occasionally use R, it is more common to test whether the difference between means (group averages) is statistically significant, usually by using a statistic called the ______, or other statistical tests.
statistical significance
Whenever researchers obtain a correlation coefficient (r), they not only establish the direction and the strength (effect size) of the relationship but also determine whether the correlation is _____________
Statistical significance
__________ is related to effect size; usually, the stronger a correlation (the larger its effect size), the more likely the correlation will be statistically significant.
An association claim
____________- describes the relationship found between two measured variables.
scatterplot
a _________ is usually the best way to represent the data
t-test
a statistical test used to evaluate the size and significance of the difference between two means
Covariance
causation 1___________ of cause and effect. There must be correlation, or association, between the cause variable and the effect variable.
Internal validity.
causation 3________- There must be no plausible alternative explanations for the relationship between the two variables.
Temporal precedence.
causation 2__________ The causal variable must precede the effect variable; it must come first in time.
positive, negative, and zero
the main types of associations:
scatterplots and correlation coefficient r
the nature of the association can be described with _____ and the _____
spurious association
the original relationship is referred to as a ___, the association is only there because of some third variable.
restriction of range.
In a correlational study, 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. This situation is known as ________
moderator
In association research, when the relationship between two variables changes depending on the level of another variable, that other variable is called a _________ (making the relation more or less intense)
curvilinear association (or curvilinear correlation)
In rare cases, when a study reports that there is no relationship between two variables, the relationship might truly be zero. In other cases, however, there might be a ________, in which the relationship between two variables is not a straight line—for example, the relationship might be positive up to a point, and then become negative.
