Ch 3

margin of error of the estimate

A statistic, based in part on sample size for a poll, indicating the probable true value in the population.

correlational study

A study that includes two or more variables, in which all of the variables are measured; can support an association claim.

internal validity

One of three criteria for establishing a causal claim; the ability to rule out alternative explanations for a causal relationship between two variables. also called third variable criterion

independent variable

The experimental factor that is manipulated; the variable whose effect is being studied.

Prioritizing Validities

Which validity is appropriate to interrogate for every study? Which validities are not always relevant for a study? Why can't researchers achieve all four validities in a single study? Which two validities are most often in trade-off? Which validity is most under the researcher's control?

association claim

a claim about two variables, in which the value (level) of one variable is said to vary systematically with the value of another variable

causal claim

a claim arguing that a specific change in one variable is responsible for influencing the value of another variable

frequency claim

a claim that describes a particular rate or degree of a single variable

Scatterplot

a graphical representation of an association, in which each dot represents one participant in the study measured on two variables

zero association

a lack of systematic association between two variables. also called zero correlation

Type II error

a miss in the statistical inference process, in which researchers conclude that their study has not detected an effect in a population when there really is one

conceptual definition

a researcher's definition of a variable at the theoretical level. Also called construct

experiment

a study in which one variable is manipulated and the other is measured

measured variable

a variable in a study whose level (values) are observed and recorded

manipulated variable

a variable in an experiment that is a researcher controls, such as by assigning participants to its different levels (values)

construct

a variable of interest, stated at an abstract level, usually defined as part of a formal statement of a psychological theory

conceptual variable

a variable of interest, stated at an abstract, or conversational, level. also called construct

positive association

an association in which high levels of one variable go with high levels of the other variable, and low levels of one variable go with low levels of the other variable. positive correlation

negative association

an association in which high levels of one variable go with low levels of the other variable, and vice versa. Also called inverse association, negative correlation

constant

an attribute that could potentially vary but that has only one level in the study in question

Variable

an attribute that varies, having at least two levels, or values

construct validity

an indication of how well a variable was measured or manipulated in a study

external validity

an indication of how well the results of a study generalize to contexts besides those of the study itself

Why do we normally consider statistical validity when interrogating association claims but not when interrogating frequency claims?

because researchers use statistical techniques to analyze association claims

what type of claim is this

causal

To evaluate how well a study supports a frequency claim, you need to focus on evaluating which of the following validities?

construct validity & external validity

interrogating association claims

construct validity, external validity, statistical validity

interrogating frequency claims

construct validity, external validity, statistical validity

which validities should be prioritized

construct, statistical & internal

three criteria for causation

covariance, temporal precedence, internal validity

three necessary criteria for causal claims are

covariance, temporal precedence, internal validity

Interrogating Causal Claims

covariance, temporal precedence, internal validity (priority)

Type I

false positive result in the statistical inference process, in which researchers conclude that there is an effect in a population, when there really is none

dependent variable

in an experiment, the variable that is measure. in a multiple-regression analysis, the single outcome, or criterion variable, the researchers are most interested in understanding or predicting. also called outcome variable

internal validity

no alternative causal explanations for the outcomes

level

one of the possible variations, or values, or a variable. also called condition

temporal precedence

one of three criteria for establishing a causal claim, stating that the proposed causal variable comes first in time, before the proposed outcome variable

Dr. Ellison finds a relation between amount of sleep and problem solving ability. Specifically, having more sleep the night before an exam is associated with higher scores on two measures of problem solving. This is an example of which type of association?

positive association

one way to ensure internal validity in your research study is to

randomly assign participants from the population

statistical validity

statistical conclusions are appropriate and reasonable

Validity

the appropriateness of a conclusion or decision

claim

the argument a journalist, researcher, or scientist is trying to make

covariance

the degree to which two variables vary together. also one of three criteria for establishing a causal claims, which states that, in a study's results, the proposed outcome variable

statistical validity

the extent to which statistical conclusions derived from a study are accurate and reasonable. also called statistical conclusion

Generalizability

the extent to which the subjects in a study represent the populations they are intended to represents; how well the settings in a study represent other settings or contexts

Which of the following is a constant in this study/headline? "Female Engineering Majors' Effort on Math Problems Depends on Sex of Role Model"

the sex of the participants

operational definition

the specific way in which a concept of interest is measured or manipulated as a variable in a study. also called operationalization or operational variable

random assignment

the use of a random method to assign participants into different experimental groups

correlate

to occur or vary together (covary) systematically, as in the case of two variables

Operationalize

to turn a conceptual definition of a variable into a specific measured variable or manipulated variable in order to conduct a research study

external valildity

to whom, what, or where can we generalize

drinking champagne prevents demential in rats. what is/are are the variable

type of drink and dementia

Are the variables measured or manipulated?

type of drink is manipulated and dementia is measured