Psychology Statistics midterm Flashcards

Terms Definitions
mid level height
a subset of the population
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
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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