Descriptive statistics

Descriptive statistics - Test Hypotheses that do not...

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Descriptive statistics - Central Tendencies o Mean: arithmetic average o Median: middle number o Mode: most frequent score - Variance: deviation from the mean o Range: variability in a data set o Standard Deviation: Square root of Variance - Inferential statistics o Determine whether relationships or differences we observe actually oceur in the population o Whether the differences we observed occurred by chance - There are 2 types of inferential statistics: o Parametric statistics Allow us to estimate parameters (eg. Means and standard deviations) Used with interval or ratio data REQUIRES NORMALITY Requires homoschedasticity There o Non parametric statistics
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Unformatted text preview: Test Hypotheses that do not involve parameters Data are nominal or ordinal Data are not normally distributed Spearman rank correlation, chi-square-What does statistical significance mean? o There is only a small probability that what we found was due to chance alone o That small chance probability goes by various names: Type 1 error Alpha level (pre determined by investigator Symbolized by an italicized p (observed)-In Psychology alpha is usually 5% or .05 o If our results cannot be obtained by chance more than 5 times in 100 random trials our results are statistically significant...
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This note was uploaded on 04/17/2008 for the course PSYCH 256 taught by Professor Dasilva during the Fall '07 term at Calvin.

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