Statistics Refresher Flashcards
definition of measurement
assigning numbers or symbols to describe things based on set rules.
what is a scale?
a set of numbers whose properties model the empirical properties of an object the numbers are assigned to
what is an error?
collective influence of all the factors on a test score or measurement beyond those specifically measured by the test/measurement
types of scale based on the variable being measured
discrete scales and continuous scales
describe nominal scale
involves classification or categorization of based on one or more distinguishing characteristics
describe ordinal scale
classification and rank ordering on some characteristics
alfred binet believed that the data derived from an intelligence scale is {}
ordinal in nature: classify and rank people on the basis of their performance
plot twist in ordinal scale
ordinal scales imply nothing about how much greater one ranking is than another because the numbers do not indicate units of measurement
they only show order not precise amounts
characteristics of interval scales
permit categorization, ranking, and contain equal intervals between numbers
characterization of ratio scale
categorization, ranking, equal interval, and absolute zero
the level of measurement most frequently used in psychology
ordinal scale
why would psychologists want to treat their assessment data as interval when those data would better describe as ordinal?
for the flexibility for which the data can be manipulated statistically
what is frequency distribution
the scores and the number of times they occurred is listed side-by-side
a statistic that indicates the average or midmost score between the extreme scores in a distribution
measures of central tendency
how to find the arithmetic mean
sum of observations (tests scores) divided by the # of observations
conditions for arithmetic mean
most appropriate MCT for interval and ratio data when the distributions are believed to be normal
defined as the middle score of the distribution
the median
conditions for median
most appropriate MCT for ordinal, interval, and ratio
particularly useful when relatively few scores fall at the high end of the distribution or relatively few scores fall at the low-end of distribution
the most frequently occurring score
the mode
conditions for mode
appropriate for nominal data
useful in the analysis of a qualitative or verbal nature
indication of how scores in a distribution are scattered or dispersed
range
the standard deviation is the…
square root of the variance
condition for the meaningful interpretation of standard deviation
test-score distribution should be relatively normal
it is the nature to which symmetry is absent; indication of how the measurements in a distribution are distributed
skewness
