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PSY 231: FINAL EXAM DEFINITIONS
Sampling Error
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the difference between the observations in a population and in the sample that represents that population in a study
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Descriptive Statistics
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measures that help us summarize data sets
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Inferential Statistics
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a set of statistical procedures use by researchers to test hypotheses about populations
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Distribution |
a set of scores
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Central Tendency
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representation of a typical score in a distribution
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Variability |
the spread of scores in a distribution
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Mean |
the calculated average of the scores in a distribution
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Median
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the middle score in a distribution, such that half of the scores are above and half are below that value
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Mode
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the most common score in a distribution
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Outliers
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extreme high or low scores in a distribution
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Reaction Time
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measurement of the length of time to complete a task
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Range |
the difference between the highest and lowest scores in a distribution
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Standard Deviation
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a measure representing the average difference between the scores and the mean of a distribution
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Variance
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the standard deviation of a distribution squared
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Degrees of Freedom
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number of scores that can vary in the calculation of a statistic
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Frequency Distribution
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a graph of a distribution showing the frequency of each response in the distribution
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Bar Graph
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a graph of the means for different conditions in a study where the bar height represents the size of the mean
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Line Graph
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a graph of the means for different conditions in a study where each mean is graphed as a point and the points are connected in a line to show differences between mean scores
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Scatterplot
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a graph showing the relationship between two dependent variables for a group of individuals
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Predictor Variable
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the dependent variable in a correlational study that is used to predict the score on another variable
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Outcome Variable
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the dependent variable in a correlational study that is being predicted by the predictor variable
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Scientific/Alternative Hypothesis
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the hypothesis that an effect or relationship exists (exists in a specific direction) in the population
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Null Hypothesis
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hypothesis that an effect or relationship does not exist (or exists in the opposite direction of the alternative hypothesis) in the population
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Two-tailed Hypothesis
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both directions of an effect or relationship are considered in the alternative hypothesis of the test
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One-tailed Hypothesis
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only one direction of an effect or relationship is predicted in the alternative hypothesis of the test
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Distribution of Sample Means
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the distribution of all possible sample means for all possible samples from a population
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Confidence Interval
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range of values that the population mean likely falls into with a specific level of certainty
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Alpha Level
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probability level used by researchers to indicate the cutoff probability level (highest value) that allows them to reject the null hypothesis
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p Value
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probability value associate with an inferential test that indicates the likelihood of obtaining the data in a study when the null hypothesis is true
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Significant Test
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the p value is less than or equal to alpha in an inferential test, and the null hypothesis can be rejected
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Critical Region
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the most extreme portion of a distribution of statistical values for the null hypothesis determined by the alpha level (typical 5%)
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Type I Error
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error made in a significance test when the researcher rejects the null hypothesis when it is actually true |
Type II Error
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Error made when in a significance test when the researcher fails to reject the null hypothesis when it is actually false
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Power |
ability of a significance test to detect an effect or relationship when one exists (equal to 1- the probability of a Type II error)
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Survey Research
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a research study that uses the survey observational technique to measure behavior
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Descriptive Research Question
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a research question that asks about the presence of behavior, how frequently it is exhibited, or whether there is a relationship between different behaviors
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Predictive Research Question
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a research question that asks if one behavior can be predicted from another behavior to allow predictions of future behavior
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Casual Research Question
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a research question that asks what causes specific behaviors to occur
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Psychometrics |
area of psychological research that involves the development, validation, and refinement of survey and tests for measuring psychological constructs
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Open-Ended Response Scale
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participants respond to survey questions in any manner they feels is appropriate for the question
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Close-Ended Response Scale
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participants respond to survey questions according to the response options provided by the researcher
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Construct Validity
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indicates that a survey measures the behavior it is designed to measure
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Nonresponse Error
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sampling error that occurs when individuals chosen for the sample do not respond to the survey, biasing the sample
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Coverage Error
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sampling error that occurs when the sample chosen to complete a survey does not provide a good representation of the population
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Criterion-Related Validity
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determining the validity of the scores of a survey by examining the relationship between the survey scores and other established measures of the behavior of interest
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Social Desirability Bias
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bias created in survey responses from respondents' desire to be viewed more favorably by others, typically resulting in over reporting of "positive" behaviors and underreporting of "negative" behaviors
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Test-Retest Reliability
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indicates that the scores on a survey will be similar when participants complete the survey more than once
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Attrition/Mortality
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occurs when participants choose not to complete a study
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Testing Effects
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occur when participants are tested more than once in a study with early testing affecting later testing
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Internal Consistency
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a form of reliability that tests relationships between scores on different items of a survey
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Split-Half Reliability
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method of testing scores' internal consistency that indicates if the scores are similar on different sets of questions on a survey that address similar topics
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Cronbach's Alpha
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method of testing scores' internal consistency that indicates the average correlation between scores on all pairs of items on a survey
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Correlational Study
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a type of research design that examines the relationships between multiple dependent variables, without manipulating any of the variables
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Descriptive Research Question
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a research question that asks about the presence of behavior, how frequently it is exhibited, or whether there is a relationship between different variables
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Predictive Research Question
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a research question that asks if one behavior can be predicted from another behavior to allow predictions of future behavior
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Predictor Variable
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the dependent variable in a correlational study that is being predicted by the predictor variable
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Third-Variable Problem
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the presence of extraneous factors in a study that affect the dependent variable can decrease the internal validity of the study
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Outcome Variable
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the dependent variable in a correlational study that is being predicted by the predictor variable
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Positive Relationship
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a relationship between variables characterized by an increase in one variable that occurs with an increase in the other variable
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Negative Relationship
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a relationship between variables characterized by an increase in one variable that occurs with a decrease in the other variable
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Random Assignment
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participants are randomly assigned to levels of the independent variable in an experiment to control for individual differences as an extraneous factor
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Quasi-Experiment
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a type of research design where a comparison is made, as in an experiment, but no random assignment of participants to groups occur
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Pretest-Posttest Design
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a type of research design (often a quasi-experiment) where behavior is measured both before and after a treatment or condition is implemented
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History Effect
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events that occur during the course of a study to all or individual participants that can result in bias
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Nonequivalent Groups
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groups compares in a study were participants are not randomly assigned
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Regression Toward the Mean
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can occur when participants score higher or lower than their personal average- the next time that are tested, they are more likely to score near their personal average, making scores unreliable
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Testing Effects
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occur when participants are tested more than once in a study with early testing affecting later testing
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Soloman Four-Group Design
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pretest-posttest design with two sets of nonequivalent groups, one set that takes the pretest and posttest and one set that takes only the posttest
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Time Series Design
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a research design where patterns of scores over time are compared from before a treatment is implemented and after a treatments is implemented
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Interrupted Time Series Design
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a time series design where the "treatment" is an independent event, such as a historical event
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Non interrupted Time Series Design
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a time series design where the "treatment" is implemented by the researcher
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History Effect
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events that occur during the course of a study to all participants or to individual participants that can result in bias
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Maturation |
natural changes that occur to the participants during the course of a study that can result in bias
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Attrition/Mortality
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occurs when participants choose not to complete a study
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Longitudinal Design
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a developmental design where a single sample of participants is followed over time and tested at different ages
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Within-Subjects Variable
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each participant experiences all levels of the variable
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Attrition/Mortality
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occurs when participants choose not to complete a study
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Testing Effects
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occur when participants are tested more than once in a study with early testing affecting later testing
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Between-subjects Variable
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each participant experiences only one level of the independent variable
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Cross-sectional Design
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a developmental design where multiple samples of participants of different ages are tested once
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Generation/Cohort Effects
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a confound that can occur in cross-sectional designs due to different experiences that different generations have
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Cohort-Sequential Design
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a developmental design where multiple samples of participants of different ages are followed over time and tested at different ages
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Small-n Design
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an experiment conducted with one or a few participants to better understand the behavior of those individuals
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Baseline Measurement
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measurement of behavior without a treatment used as a comparison
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Discrete Trails Design
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a small-n design that involved a large number of trails completed by one or a few individuals and conducted to describe basic behaviors
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Baseline Design
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a small-n design that involves baseline measurements of behavior as compared with measures of behavior during the implementation of a treatment
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Carryover Effects
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occur when participants' experience in one condition affects their behavior in another condition of a study
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A-B-A/Reversal Design
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a small-n, baseline design where the baseline behavior is measured, followed by implementation of a treatment, followed by another baseline measure after the treatment has ended
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