R.M.

the consistency of a set of scores

whether the measure ofcentral tendancy used indeed depicts what scores in the distribution are like

whether the mean or median accurately predicts the scores of individuals in a group

whether a generalization about a population based on a sample is likely tobe a good guess

reference point from which the amount of spread in a distribution of scores is measured

• 1. Range
• 2. Absolute mean deviation or Average absolute deviation (ADD)
• 3. Median absolute deviation (MAD)
• 4. Variance and standard deviation

largest score - smallest score

• 1. Find median of set of scores
• 2. Find deviation from median by subtracting median from each score
• 3. Take absolute value of each deviation
• 4. Find median of ab. deviations

Sensitivity increases with the number of possible values that can be reliably used

refers to the extent to which a test uses items representative of the area you are trying to measure

refers to the degree to which test scores correlate with some criterion of interest (some direct and independent measure of what you are trying to measure)

• 1. to obtain more convenient numbers
• 2. to meet the assumptions of certain stats
• 3. to obtain pretty graphs
• 4. to meet the assumptions ofsome theory
• 5. to minimize the influence of extreme scores
• 6. to allow for comparison across different data sets such as college exams

• percentages
• z scores

• how far youare from the mean in standard deviations units
• Allow you to compare people even if measured using different scales

• 1. Find z score for each number (use standard deviation for samples)
• 2. Multiply z scores for each pair together
• 3. Add the products of the multiplications together
• 4. Divide by the number of pairs -1

concerns the quantitative relationships between physical stimuli and the psychological experience of them

• S = K log R
• Sensation (psychological intensity) increases as the logarithm of the physical intensity of a stimulus

• S = k R^N
• Sensation (psychological intensity) increases as th n^th power of the physical intensity of a stimulus

is a field of study having to do with the measurement of personality "traits", intelligence, knowledge, attitudes..

• assigning numbers to the psychological experiences caused by a set of stimuli that may not vary along a simple physical dimension
• However the sest of stimuli do vary along some psychological dimension

• 1. show that changes in Y did not occur until after the changes in X (Temporal precedence rule)
• 2. show that X and Y are related (covariation rule)
• 3. show that other explanations for the relationship between X and Y can be ruled out (internal validity rule)

show that Y didnt occur until after changes in X

show that X and Y are related

show that other explanations for the relationship between X and Y can be ruled out

• 1. manipulation of X
• 2. comparison of the effects of various levels of X on Y
• 3. Subjects which begin the experiment equivalent on all important characteristics for each levelof X (1 method of doing this is by random assignment)
• 4. control over all other important variables so that all subjects are treated exactly the same except for X (the I.V.)

• each subject contributes a score (or a mean) for just one level (or amount) of the predictor or independent variable (X)
• there are at least 2 leavels

• selection bias
• differential attrition or mortality
• interaction of selection bias with treatment

Each subject contributes a score (or a mean) for all levels (or amounts) of the predictor or independent variable (X) and there are at least 2 levels

• maturation
• instrument decay
• history
• testing
• statistical regression

• No comparison
• 1 level of the variable of interest may be introduced by the researcher or simply identified by the researcher
• Since there is no comparison obviously comparisons are neither b/w or w/in
• Few if any alternative explanations for the outcome (Y) can be eliminated

• X is selected
• X is "manipulated" (introduced by researcher)

• 1. X is simply measured
• 2. X is selected
• 3. X is manipulated

• 1. X is simply measured
• 2. X is selected
• 3. X is manipulated

the differential loss of subjects from the various comparison groups over the course of a study

• the treatment produces selection bias
• Thus one or more levels of the I.V. cause some subjects to drop out making the group unequal

the subjects in the various treatment groups communicate with eachother so that the participants in 1group learn something about the experiment that was intended for other groups, not theirs

refers to the situation in which untreated individuals or groups learn of the treatment received by others and demand the same treatment or equally good

involves the situation in which individuals in an untreated or control group learn that others are receiving special treatment and become less productive, efficient, or motivated than they would have been because of feelings of resentment

refers to the possibility that the observed effect in a w/in subjects design is due to changes in internal conditions over time rather than the variable of interest

• refers to the possible effects of already having taken a test on a participants score when the participant takes the test again.
• Also called carry over

occurs when performance on a particular condition depends partially upon the particular condition that preceded it

refers to a threat to internal validity that occurs when an effect may be due to external (outside/environmental) events that occur b/w tests rather than the variable of interest

occurs when a measurement device changes calibration or an observer changes criteria over time

• refers to the fact thatextreme scores in a distribution tend to move toward the mean of a distribution with repeated testing.
• A function of the reliability of the test

statistical regression is more likely to occur