Privitera chapter 2
Why are relative frequency reported we percents
Easier to read than decimals
Cumulative frequencies can be added from the top ___ and bottom ___
Down, up
Summary display for a distribution of data organized or summarized in terms of how often ( or frequently) scores occur
Frequency distribution
Histograms summarize
Frequency of continuous data that is quantitative
bar chart
Graphical display used to summarize frequency of discrete and categorical data distributed in whole units or classes
Grouped data often summarized graphically using
Histogram
Problems with open intervals
Make it difficult to identify if outliers exist in data set
Difference between histogram and stem and leaf
Stem and leaf display actual scores and histogram lists frequencies
cumulative frequency
Sum of scores across each range and always sums to the total number of scores in a distribution
A cumulative percent distribution is
Summary display that distributes sum of relative percents across series of intervals
Relative frequency =
frequency/sum of all frequencies
frequency polygon
graph of a frequency distribution that shows the number of instances of obtained scores, usually with the data points connect by straight lines. Dot and line graph plotted at midpoint of each interval
Real range
one more than the difference between the largest and smallest value in a data set
rules for a simple frequency distribution
-each interval is defined -each interval is equidistant -no interval overlaps -all values are rounded to same degree of accuracy measured in original data
How to identity rank of individual
1- identify interval within which a specified point falls 2- identify real range for interval identified 3- find position of percentile point within the interval , multiply fraction by width of real range 4- identify percentile point
3 rules of histograms
1- vertical rectangle reps each interval and height equals frequency 2- base of es rectangle behind and ends at upper and lower boundaries or each interval 3- each rectangle touches adjacent rectangles at boundaries of each interval
Sum of all proportions for a distribution
1.0
Relative percent sums to
100%
What is the recommended number of intervals that should be included in a simple frequency distribution
5-20 intervals
Ogive
A line graph that depicts cumulative frequencies. Dot and lime graph plotted at upper boundary of each interval
stem and leaf plot
A method of graphing a collection of numbers by placing the "stem" digits (or initial digits) in one column and the "leaf" digits (or remaining digits) out to the right.
When cumulative frequencies from bottom up you typically want to discuss data in terms of
At most, less than, at or below
When comulating frequencies grim the top down you want to discuss data in terms of
At or above
Similar to histogram except bars seperated from one another
Bar chart
degree of accuracy
Being free from errors within a specified tolerance.
summary display that distributes the sum of frequencies across a series of intervals
Cumulative frequency
Ogive typically summarized what type of frequency distribution
Cumulative percent distribution
Proportion is
Part of portion of all measured data
Used to effectively summarize frequency data
Pictures and pictographs
Summary display that distributes the proportion of scores in each interval. It's computed as frequency increases each interval divided by total number of frequencies recorded
Relative frequency
Ungrouped data can be summarized using
Relative frequency, relative percent, cumulative relative frequency, relative percent and cumulative relative percent
Summary display that distributes the percentage of scores occurring in each interval relative to all scores distributed
Relative percent distribution
bottom-up frequency
Start with lowest at bottom top is sum of all
When would a researcher construct a relative frequency table
To summarize large data sets
True or false whether you consulate a frequency distribution from bottom up or top down depends on how you wanna discuss data
True
When dependent variable is qualitative or categorical or number of different scores is small data is then
Ungrouped, intervals not constructed
Percentile point is
Value of a score on a measurement scale below which a specified percentage of scores in a distribution fall
percentile rank
the percentage of scores below a specific score in a distribution of scores
interval width
the range of values contained in each interval of a grouped frequency distribution. Real range divided by number of intervals