PSY230 - Chapter 2

When cumulating frequencies from the bottom up, the data are discussed in terms of:

"at most"; "less than"; and "at or below"

When cumulating frequencies from the top down, the data are discussed in terms of

"at or above"

what are the three steps to construct a frequency distribution?

1) find the real range; 2) find the interval width; 3) construct the frequency distribution

the sum of all relative frequencies across all intervals is equal to ___

1.00

what is the recommended number of intervals that should be included in a simple frequency distribution ?

5 to 20. any more is too much, and any less isn't helpful

percentile point

the value of a score on a measurement scale below which a specified percentage of scores in a distribution fall

frequency distribution

A summary chart, showing how frequently each of the various scores in a set of data occurs

relative precent distribution

a summary of display that distributes the percentage of scores occuring in each interval relative to all scores distributed

interval boundaries

the upper and lower limits for each interval in a grouped frequency distribution

cumulative percents

a summary display that distributes the sum of relative percents across a series of intervals

when would a researcher construct a relative frequency table?

To summarize large data sets

Interval

a discrete range of values within which the frequency of a subset of scores is contained

Ogive

a dot-and-line graph used to summarize the cumulative percent of continuous data at the upper boundary of each interval

frequency polygon

a dot-and-line graph used to summarize the frequency of continuous data at the midpoint of each interval

Histogram

a graphical display used to summarize the frequency of continuous data that are distributed in numeric intervals (grouped)

proportion

a part or portion of all measured data. the sum of all proportions for a distribution of scores is 1.0

grouped data

a set of scores distributed into intervals, where the frequency of each score can fall into any given interval

ungrouped data

a set of scores or categories distributed individually, where the frequency for each individual score or category is counted

simple frequency distribution

a summary display for (1) the frequency of each individual score or category (ungrouped data) in a distribution or (2) the frequency of scores falling within defined groups or intervals (grouped data) in a distribution

relative frequency distribution

a summary display that distributes the proportion of scores in each interval. It is computed as the frequency in each interval divided by the total number of frequencies recorded

cumulative frequency distribution

a summary display that distributes the sum of frequencies across a series of intervals

cumulative relative frequency distribution

a summary display that distributes the sum of relative frequencies across a series of intervals

open interval/open class

an interval with no defined upper or lower boundary

cumulative frequencies can be added from the top ___ and the bottom ___.

down, up

outliers

extreme values that don't appear to belong with the rest of the data

A ___ is a summary display for a distribution of date organized it summarized in terms of how often scores occur

frequency distribution

bar chart/bar graph p57

graphical display used to summarize the frequency of discrete and categorical data that are distributed in whole units or classes

why is it generally inappropriate to include an open interval in a simple frequency distribution?

including the open interval can make it difficult to identify if outliers exist in a data set

real range

one more than the difference between the largest and smallest value in a data set

relative frequencies are commonly reported in academic journals as percents, why?

researchers often find percents easier to read than decimals

upper boundary

the largest value in each interval of a frequency distribution

frequency

the number of times or how often a category, score, or range of scores occurs

percentile rank

the percentage of scores below a certain point

interval width

the range of values contained in each interval of a grouped frequency distribution

lower boundary

the smallest value in each interval of a frequency distribution