
constructs
attributes or characteristics that cannot be directly observed
(i.e. intelligence, hunger, anxiety)

operational definition
 defines a construct in terms of external behaviors that can be observed and measured
 (i.e. IQ test performance, hours since eating)

discrete variable
separate, indivisible categories
(i.e. male, female)

continuous variable
infinite number of possible values; each measurement is an interval that must be defined by boundaries

real limits
boundaries of intervals for scores; exactly 1/2 way between the scores above and below
 1) upper real limit
 2) lower real limit

nominal scale
set of categories that have different names; does not make any quantitive differences

ordinal scale
 set of categories that are organized in and ordered sequence corresponding to differences in magnitude
 (example: ranking  1st, 2nd, 3rd place)

interval scale
series of ordered categories that form a series of intervals that are exactly the same (inches, seconds, lbs); zero is arbitrary and holds no value

ratio scale
anchored by a a zero point that represents complete absence; measures direction and size of magnitude

order of mathematical operations:
 1. ( )
 2. exponents
 3. x or /
 4. sigma
 5. + or 

