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I/O Psych 542
Exam 2 Part 1
Question | Answer |
---|---|
Assumptions (as in statistical) | a characteristic that we ideally require the population from which we are sampling to have so that we can make accurate inferences |
Robust | hypothesis tests that produce fairly accurate results even when the data suggest that the population might meet some of the assumptions |
Parametric Tests | an inferential statistical analysis that is based on a set of assumptions about the population – three main assumptions for parametric testing |
three main assumptions for parametric testing | *dv assessed w/a scale measure (equal distance between #s) *partic. randomly selected *distr. of pop. of interest must b normal–bc hypothesis tests w/sample means vs. individual scores, if samp. size is 30 (based on central limit theorem)assumption met |
Non-parametric Tests | Non-parametric Tests – an inferential statistical analysis that is not based on a set of assumptions about the population |
Critical Values | a test statistic value beyond which we will reject the null hypothesis, often called a cutoff |
Critical Regions | the area in the tails of the distribution within which we will reject eh null hypothesis if our test statistic falls there |
p Level or Value | the probability used to determine the critical values, or cutoffs, in hypothesis testing; also called alpha |
statistically significant | describes a finding for which we have rejected the null hypothesis because the pattern in the data differs from what we would expect by chance |
One Tailed Test | a hypothesis test in which the research hypothesis is directional, positing either a mean decrease or a mean increase in the dependent variable, but not both, as a result of the independent variable |
Two-Tailed Test t-Statistic | a hypothesis test in which the research hypothesis does not indicate a direction of mean difference or change in the dependent variable but merely indicates that there will be a mean difference |
Single Sample t-Test | a hypothesis test in which we compare data from one sample to a population for which we know the mean but not the standard deviation |
Paired Samples t test | a test used to compare two means for a within-groups design, a situation in which every participant is in both samples, also called a dependent samples t-test. Ex: pre-test/post-test, paired samples (husband/wife, parent/child), repeated measures design |
Independent-Samples t-Test | a hypothesis test used to compare two means for a between-groups design, a situation in which each participant is assigned to only one condition. Ex: two completely different sets of samples |
Degrees of Freedom | the number of scores that are free to vary when estimating a population parameter from a sample |
Pooled Variance | a weighted average of the two estimates of variance – one from each sample – that are calculated when conducting an independent-samples t test |
ANOVA | a hypothesis test typically used with one or more nominal independent variables (with at least three groups overall) and a scale dependent variable (analysis of variance) |
F statistic | a ratio of two measures of variance: (a) between-groups variance, which indicates differences among the sample means and (b) within-groups variance, which is essentially an average of the sample variances |
Between group variance | an estimate of the population variables based on the differences among the means (ex: comparing the pace people talk from Chicago, Shreveport and New York) |
Within Group Variance | an estimate of the population variance based on the differences within each of the three (or more) sample distributions (ex: comparing the pace people talk in Shreveport – not everyone in the same city talks the same speed) |
1 way ANOVA | a hypothesis test that includes one nominal independent variable with more than two levels and a scale dependent variable |
Within Groups ANOVA | a hypothesis test in which there are more than two samples and each sample is composed of the same participants (aka: repeated measures ANOVA) |
Between Groups ANOVA | a hypothesis test in which there are more than two samples and each sample is composed of different participants |
homoscedastic | describes populations that have the same variance; also called homogeneity of variance |
Heteroscedastic | describes populations that have different variances |
Post Hoc Tests | a statistical procedure frequently carried out after we reject the null hypothesis in an analysis of variance; it allows us to make multiple comparisons among several means |
Planned Comparisons | a.Tukey HSD Test –widely used post-hoc test that determines differences between means in terms of standard error; the HSD is compared to a critical value – sometimes called the q test b.Scheffe’s Test – post hoc test –one of the more conservative tests |
Factor | describes an independent variable in a study with more than one independent variable |
Cell | a box that depicts one unique combination of levels of the independent variables in a factorial design |
2 way ANOVA | a hypothesis test that includes two nominal independent variables, regardless of their numbers of levels, and a scale dependent variable |
Factoral ANOVA | a statistical analysis used with one scale depdenent variable and at least two nominal independent variables (sometimes called factors); also called a multifactorial ANOVA |