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psy400ch14p333
Analyzing Your Data II: Specific Approaches
| Term | Definition |
|---|---|
| computerized adaptive testing, or CAT, adjusts the level of questions in response to | the estimated ability of the person taking the test; saves time and maintains measurement precision. |
| Make sure you get the first bunch of questions correct if | you're taking an adaptive test |
| NHST | Null Hypothesis Significance Testing |
| Analysis of variance (ANOVA): A statistical technique to test | for differences among means |
| Parametric statistical test: requires data to he interval or ratio level and have a mean and standard deviation | makes strong assumptions about the distribution of measurements in the population (t test or ANOVA) |
| Nonparametric statistical tests: make few assumptions about the distribution of measurements in the population and | does not require data to be interval or ratio level |
| t test, one sample | compares the mean of a single sample to a specified value |
| Wilcoxon signed-rank test | A nonparametric alternative to the one-sample or matched-pairs t tests |
| Nonparametric alternative one sample to t test | one sample Wilcoxon signed rank test |
| Degrees of freedom (df) | The number of values that are free to vary in the computation of a statistic |
| For a one-sample t test, there are | n — 1 degrees of freedom |
| t test, independent samples | for comparing the means of two independent samples |
| t test, independent samples Assumptions: | Interval- or ratio-level data. Random sampling and independence of observations/cases. The two populations are normally distributed and have equal variances. |
| Welch's t test | an independent-samplest t test that takes into account unequal variances between the two groups |
| Mann-Whitney U test or Wilcoxon rank-sum test | A nonparametric alternative to the independent-samples t test. |
| t test, matched pairs | compares the means of two matched samples (two measurements from the same participants or participants matched on some criteria (e.g., academic achievement) |
| Matched-Pairs t Test Assumptions: | Interval- or ratio-level data. Random sampling, Independent observations (between cases, not within). Difference scores are normally distributed. |
| Matched-Pairs t Test Nonparametric alternative | Wilcoxon signed-rank test |
| One-way analysis of variance (ANOVA) | tests for differences of means on a single factor. |
| If we wish to compare the means for three or more samples on a single factor, then | we employ one-way analysis of variance (ANOVA) |
| Independent-Groups One-Way ANOVA (Between Subjects) Assumptions: | Interval- or ratio-level data; Random sampling and independence of observations. populations normally distributed, homogeneity of variance |
| Kruskal-Wallis test | A nonparametric alternative to one-way analysis of variance. |
| ANOVA table | organizes and displays the results of analysis of variance |
| Sums of squares | measures the amount of variability in data, including between-subjects, within-subjects, and total sums of squares |
| The between-subjects sum of squares shows the extent to which | the group means deviate from the overall mean |
| The within-subjects sum of squares indicates the extent to which | each data point deviates from its group mean |
| Each mean square value is computed by dividing | the corresponding sum of squares by its associated degrees of freedom |
| Each mean square value | is an estimate of the population variance |
| If the between-subjects mean square is considerably larger than the within-subjects mean square, | this is evidence that the population means differ from one another |