Vocab Flashcards
measurement:
process of assigning numerals to variables to represent quantities of characteristics according to certain rules
continuous variable:
A quantitative variable that can theoretically take on values along a continuum
discrete variable:
A variable that can only be measured in separate units and that cannot be measured in intervals of less than 1
dichotomy (dichotomous variable):
A nominal variable having only two categories, such as yes/no and male/female; a binomial variable
precision:
exactness of measure
constructs:
concepts that represent nonobservable behaviors or events
level of measurement/scales:
The precision of a scale based on how a characteristic is measured; nominal, ordinal, interval and ratio levels
nominal
classificatory scale, qualitative (gender, blood type, diagnosis). These are mutually exclusive in that you cannot belong to more than one group
ordinal rank:
ordered on the basis of an operationally defined characteristic or property. (manual muscle tests, function, pain)
interval numbers
have equal intervals but no true zero (calendar years, C or F)
ratio
numbers represent units with equal intervals, measured from true zero
reliability
The degree of consistency with which an instrument or rater measures a variable. .5 is poor. .5-.75 moderate. .75+ good.
validity:
- The degree to which an instrument measures what it is intended to measure.
- The degree to which a research design allows for reasonable interpretations from the data, based on controls (internal validity), appropriate definitions (construct validity), appropriate analysis procedures (statistical conclusion validity), and generalizability (external validity).
measurement error:
The difference between an observed value for a measurement and the theoretical true score; may be the result of systematic or random effects.
systematic error:
A form of measurement error, where error is constant across trials.
random errors:
measurement are due to chance and can affect a subjects score in an unpredictable way from trial to trial
regression toward the mean:
A statistical phenomenon in which scores on a pretest are likely to move toward the group mean on a posttest because of inherent positive or negative measurement error; also called statistical regression.
variance:
A measure of variability in a distribution, equal to the square of the standard deviation.
reliability coefficient:
true score variance/ (true score variance + error variance)=T/ (T+E)
correlation:
The tendency for variation in one variable to be related to variation in a second variable; those statistical procedures used to assess the degree of covariation between two variables
agreement:
measure used in conjunction with correlation. The degree to which values from two measurements are the same not just correlated
test-retest reliability:
The degree to which an instrument is stable, based on repeated administrations of the test to the same individuals over a specified time interval
testing effect:
The effect that occurs when a test itself is responsible for observed changes in the measured variable.
interrater reliability:
• The degree to which two or more raters can obtain the same ratings for a given variable