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
