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29 Cards in this Set
 Front
 Back
Central Tendency

way in which quantitative data tend to cluster around some value


Central Tendency

single number closest to the center of distribution; represents all the data


Average

a single value that summarizes or represents the general significance of a set of unequal values


Average

Central Tendency Number/value


Generic Quantitative Data

set denotated by X , X , Xn


Mean

adding up the values and then dividing by the number of values


Sample Mean

observations only of sample data (common mean used)


Population Mean

Observations of every single item or unit of a population


Factors of MEAN

 uses all data
 varies less then median and mode in repeated samples  used in computing other important statisticas  is unique and not neccessarily equal to any data value in the data set  effected by OUTLIERS and may not be appropriate for data sets conaining outliers (not resistant to OUTLIERS) 

Median

the middle value of the observations ( values are in ascending order)


Median

if even number of observations exists, the median is the mean of the two middle values


Factors of Median

 used to find the center or middle value
 used to determine whether a given data value falls above or below 50%  effected less then the mean by OUTLIERS 

Sample Mode

Data value that occurs the most; may not be in the center (aka crude mode or model class)


Unimodel

1 Mode


Bimodel

1 Modes


Multimodel

several Modes


No Mode

data values only occur once


Factors of MODE

 most frequent value is saught
 simplest "average" to find  can be used for group categorical data  isn't always unique 

Sample MidRange

sum of smallest and largest data value divided by 2


Factors od MIDRANGE

 not resistant to outliers
 easy to compute  uses only 2 data values  less efficient to the mean 

Symmetrical Distribution

all values of average (mean, median, mode) are the same value


Skewed Distribution

the mean shifts toward the direction of the skew (right and left skew)


Positive Skew

Right Skew; most common; mean to the right and is therefor larger then the median and mode (Mode, Median, then Mean)


Negative Skew

Left Skew; Mean is to the left (Mean, Median, then Mode)


Sample Mean Formula

write formula:


Population Mean Formula

write formula:


Left Skewed

Draw Skew


Right Skewed

Draw Skew


Symmetrical Distribution

Draw scale
