PSY302-300573824
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TESTS
Two-sample t-test: between (independent)
Definition: Testing the relationship between a categorical independent variable and a continuous independent variable, in which the categorical independent variable is a between-subjects design with two levels.
Application:
Two-sample t-test: within (related)
Definition: Testing the relationship between a categorical independent variable and a continuous independent variable, in which the categorical independent variable is a within-subjects design with two levels.
Example: http://ajp.psychiatryonline.org/cgi/content/abstract/154/9/1235
Application:
One-Way ANOVA test
Definition: Testing the relationship between a categorical independent variable and a continuous independent variable, in which the categorical independent variable is a between-subjects design with three or more levels.
Example: http://psycnet.apa.org/index.cfm?fa=buy.optionToBuy&id=1996-00479-001&CFID=6997869&CFTOKEN=33393354
Application:
Two-Way ANOVA test
Definition: Testing the relationship between two categorical independent variable and a continuous independent variable.
Example: http://neuro.psychiatryonline.org/cgi/content/abstract/10/1/34
Application: Two-Way ANOVA test analyzing relation between MMSE and generalized anxiety disorder
Correlation test
Definition: Testing the relationship between two continuous variables, either of which can be considered the independent or dependent variable.
Application:
Chi-square test
Definition: Testing the relationship between two categorical variables, either of which can be considered the independent or dependent variable.
Application:
Concepts
Standard Score
Definition: A score obtained by using the transformation z=(X-X)/S
Application:
Confidence Interval
Definition: A range of score values expected to contain the value of mu with a certain level of confidence.
Example: http://www.pediatrics.org/cgi/content/full/114/2/e220
Application:
Parametric Test
Definition: A statistical test involving hypotheses that state a relationship about a population parameter.
Example: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1295297/
Application: This study used both parametric and non-parametric tests
Nonparametric Test
Definition: A statistical test involving hypotheses that do not state a relationship about a population parameter. Also known as distribution-free test.
Example: http://www.springerlink.com/content/x70uq8766g67561h/
Application:
Statistically significant difference
Definition: The observed value of the test statistic falls into a rejection region and H0 is rejected.
Example: http://www.jstor.org/pss/2676394
Application:
Nonsignificant difference
Definition: The observed value of the test statistic does not fall into a rejection region and the null hypothesis is not rejected.
Application:
Between-subjects Design, with two groups
Definition: An experiment in which two or more groups are created.
Example: http://psycnet.apa.org/index.cfm?fa=buy.optionToBuy&id=2000-07798-009&CFID=6997869&CFTOKEN=33393354
Application: 2 x 2: Frame=promotion vs. prevention and Construal=independent vs. interdependent
Between-subjects Design, with three or more groups
Definition: A research design in which three or more groups are created
Example: http://www.jstor.org/pss/2489818
Application:
Random sampling
Definition: A sampling method in which individuals are selected so that each member of the population has an equal chance of being selected for the sample, and the selection of one member is independent of any other member of the population.
Example: http://ajph.aphapublications.org/cgi/content/abstract/87/9/1427
Application: 7119 students were randomly selected from 12 NYC high schools and 5738 students were randomly selected from 10 Chicago high schools for this study
Random Assignment
Definition: A method of assigning subjects to treatment groups so that any individual selected for the experiment has an equal probability of assignment to any of the groups and the assignment of one subject to a group does not affect the assignment of any other individual to that same group.
Example: http://ajp.psychiatryonline.org/cgi/content/abstract/154/2/147
Application: Results of findings of 8/10 clinical trials with random assignment and 8/8 without random assignment suggest that psychotherapy reduces total costs.
Independent Variable
Definition: A variable manipulated in an experiment to determine its effect on the dependent variable.
Example: http://ajph.aphapublications.org/cgi/content/abstract/87/9/1427
Application: Independent variables in this experiment were: use of condom availability programs and exposure to HIV/AIDS lessons
Levels of the Independent Variable
Definition: One value of the independent variable. To be a variable, an independent variable must take on at least two different levels.
Example: http://ajph.aphapublications.org/cgi/content/abstract/74/3/261
Application: Levels of the independent variable were smoking behavior and race
Confounds
Definition: An extraneous variable that is covarying with the independent variable, potentially masking the true effects of the independent variable on the dependent variable.
Example: http://www.pediatrics.org/cgi/content/full/114/2/e220
Application:
Dependent Variable
Definition: The variable in an experiment that depends on the independent variable. In most instances the dependent variable is some measure of a behavior.
Example: http://www.jstor.org/pss/2676394
Application:
Within-subjects Design, with two groups
Definition: A research design in which two groups of subjects is exposed to and measured under each level of an independent variable. Each person receives a treatment condition.
Example: http://www.jstor.org/pss/1131609
Application: Two groups: autistic and comparison each receiving same tests of movement, etc.
Within-subjects Design, with three or more groups
Definition: A research design in which three groups of subjects is exposed to and measured under each level of an independent variable. Each person receives a treatment condition.
Example: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1425325/
Application: Three groups tested: patrons of gay bars, patrons of gay baths and identified as a partner in a gay couple. Test was a survey of sexual behavior and factors affecting response to the AIDS epidemic taken after six months
Main effect
Definition: The mean of all subjects given one level of an independent variable, ignoring the classification by the other independent variable in a factorial design.
Example: http://www.jstor.org/pss/2676394
Application:
Interaction
Definition: A situation in a factorial design in which the effect of one independent variable depends on the level of the other independent variable with which it is combined.
Example: http://www.jstor.org/pss/2676394
Application:
Strength of Effect (Eta squared)
Definition: Eta squared is one of the effect size measures that have been developed for measuring the size of the effect of the independent variable after an experiment has been completed.
Example: http://ps.psychiatryonline.org/cgi/content/abstract/57/12/1758
Application:
Scatterplot
Definition: A plot of a bivariate distribution in which the X variable is plotted on the horizontal axis and the Y variable is plotted on the vertical axis.
Example: http://www.ingentaconnect.com/content/bpsoc/bjp/2009/00000100/00000001/art00001
Application: Scatterplot shows the relationship between fT level and AQ child scores
Positive relationship
Definition: A relationship between two variables in which, as the value of one variable increases the value of the other variable tends to increase also.
Application: Positive relationship between reported substance abuse and risky behavior in adolescents
Negative relationship
Definition: A relationship between two variables in which, as the value of one variable increases, the value of the other variable tends to decrease.
Example: http://ajph.aphapublications.org/cgi/content/abstract/74/3/261
Application: In this study there was a strong negative relationship between the age of first intercourse and the level of cigarette smoking.
No relationship
Definition: If you know one variable and know nothing about another variable.
Example: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1425325/
Application: No relationship in the change or stability in number of partners and level of agreement with health guidelines
Linear relationship
Definition: A relationship between two variables that can be described by a straight line.
Example: http://ajph.aphapublications.org/cgi/content/abstract/90/10/1582
Application:
Curvilinear relationship
Definition: Changes over the ranges of both variables
Example: http://www.psychosomaticmedicine.org/cgi/content/abstract/42/2/253
Application: For one combination of variables with test of curvilinear relationship employing polynomial regression was performed
Coefficient of Determination
Definition: The value of r2 indicating the common variance of variables X and Y.
Example: http://cjr.sagepub.com/cgi/content/abstract/32/4/401
Application:
Correlation does not equal causation
Definition: Because there is correlation between two variables does not mean one causes the other.
Application: "Many studies have documented a positive correlation between adolescent substance abuse and sexual activity but to out knowledge noe have established causality."
Extra-Credit (3 points each)
Normal Distribution
Symmetrical
Asymptotic
Continuous
Sampling Error
Definition: The amount by which a sample mean differs from the population mean
Example: http://ajph.aphapublications.org/cgi/content/abstract/91/2/292
Null Hypothesis
Definition: A statement of a condition that a scientist tentatively holds to be true about a population; it is the hypothesis that is tested by a statistical test.
Example: http://www.psychosomaticmedicine.org/cgi/content/abstract/42/2/253
Application: The null hypothesis in this study could not be proven
Alternative Hypothesis
Definition: a statement of what must be true if the null hypothesis is false.
Example: http://www.jstor.org/pss/2676394
Significance level
Definition: A probability value that provides the criterion for rejecting a null hypothesis in a statistical test.
Example: http://www.pediatrics.org/cgi/content/full/114/2/e220
Two-tailed test
Definition: A statistical test using rejection regions in both tails of the sampling distribution of a test statistic.
Example: http://www.jstor.org/pss/2676394
One-tailed test
Definition: A statistical test employing a rejection region in only one tail of the sampling distribution of the test statistic.
Example: http://www.psychosomaticmedicine.org/cgi/content/abstract/42/2/253
Application: One tailed tests of significance were used for relationship of testosterone with antisocial behavior and lack of frustration tolerance
Degrees of Freedom
Definition: The number of scores free to vary when calculating a statistic.
Type I Error
Definition: The error in statistical decision making that occurs if the null hypothesis is rejected when actually it is true of the population.
Type II Error
Definition: The error in statistical decision making that occurs if H0 is not rejected when it is false and the alternative hypothesis is true
Power
Definition: The probability of rejecting H0 when H0 is false and H1 is true.
Example: http://www.psychosomaticmedicine.org/cgi/content/abstract/42/2/253
Application: The power was shown to increase to 0.94 when a one-tailed test was used.
Pairwise comparisons
Definition: Statistical comparisons involving two means
Post-hoc comparisons
Definition: Statistical tests that make all possible pairwise comparisons after a statistically significant Fobs has occurred for the overall analysis of variance.
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