frequency distributions Flashcards
frequency distribution
an organized tabulation of the number of individuals located in each category on the scale of measurement
proportion
relative frequency (p = f / N)
percentage
100p
histogram
a graph using vertical bars such that (1) bar height corresponds to frequency, and (2) bar width extends to the real limits of score; used when data are on an interval or ratio scale
bar graph
a graph using vertical bars such that (1) bar height corresponds to frequency, and (2) there are spaces between the bars; used when data are on a nominal or ordinal scale
frequency distribution polygon
a graph using dots such that (1) dots are centered above scores, (2) dot height corresponds to frequency, and (3) a continuous line is drawn through the dots; used when data are on an interval or ratio scale
abscissa
x-axis; the horizontal line on a graph
ordinate
y-axis; the vertical line on a graph
symmetrical distribution
a distribution such that it is possible to draw a vertical line through the middle, where one side exactly mirrors the other
skewed distribution
scores pile up toward one end of the distribution
tail
the part of a skewed distribution where the scores taper off away from the score pileup at the other end
positively skewed
tail towards the right
negatively skewed
tail towards the left
(percentile) rank
the percentage of individuals in a distribution with scores at or above a particular value
percentile
a value identified by (percentile) rank
