# Psychology Statistics midterm Flashcards

Terms Definitions
 mesokurtic mid level height sample a subset of the population Reliability How stable the measure is Domain-referenced tests Attempt to measure less-defined properties (like intelligence) and need to be checked for reliability and validity Inferential statistics Prevent unreasonable conclusions from data hypothesis testing decisions are made concerning the values of parameters. key to inferential stats. it takes the data results and compares it to the population which allows you to make predictions based on the results. Construct validity External validity- Whether the test really taps the abstract concept being measured Split-half reliability Measured by comparing an individual's performance on two halves of the same test (odd vs. even questions) - reveals internal consistency. Can also increase internal consistency of a measure by performing an item analysis error factors of alpha set by the experimenter Parametric statistics like the t-test assume that the data collected is... Normally distributed Interval variables Shows order and spacing, equal space lie between the values, do not include a real zero median the point on the scale of measures where the population is centered. The measure of a population is the point that divides the distribution of scores in half. Random Sample Requires that each individual in the population has an equal chance of being selected. Probablities must stay constant from one selection to the next if more than one individual is selected. the two possible sampling situations: sampling with replacement, sampling without replacement Standard deviation Square root of the variance, tells you the average extent to which scores were different from the mean (large SD= scores were highly dispersed, SD small= scores were very close together) nominal scale names, eg. list of students in alphabetical order convicting an innocent woman of a crime is an example of what error? Type I error Typer II Error Occurs when a researcher fails to reject a null hypothesis that is really false. Person has cancer, tell them they dont directional (one tailed) test designed to detect extreme outcomes in only one specified direction of the distribution Standardized tests Test that are tried out on huge groups of people in order to create norms obstacles to using dependent -if impossible to participate in both conditions (normal vs parkinsons, men vs women)-if participation in one condition affects other conditions (conjunction fallacy, solving a reasoning problem) Typical application of hypothesis testing with two related samples Within subjects design with two conditions type I error You have committed a this error if you have rejected the hypothesis tested when it was true. More seriousmore serious two tail - non directional no prior evidenceH0: u=aH1: u NOT =a four components of statistical power 1. sample size: # of units studied2. effect size: strength of the relationship between 2 variables.3. alpha level: odds that the observed result is due to chance (normall is .05)4. power: the odds that youll observe a treatment effect when it occurs When do you accept your null? if probability of sample result is above alpha Spearman r correlation coefficient Used when the data is in the form of ranks why must you subtract the joint probabilities of a and b when doing an adding probabilities problem? So that you do not double-count your data
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