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29 Cards in this Set
- Front
- Back
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Central Tendency
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way in which quantitative data tend to cluster around some value
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Central Tendency
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single number closest to the center of distribution; represents all the data
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Average
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a single value that summarizes or represents the general significance of a set of unequal values
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Average
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Central Tendency Number/value
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Generic Quantitative Data
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set denotated by X , X , Xn
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Mean
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adding up the values and then dividing by the number of values
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Sample Mean
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observations only of sample data (common mean used)
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Population Mean
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Observations of every single item or unit of a population
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Factors of MEAN
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- 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) |
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Median
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the middle value of the observations ( values are in ascending order)
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Median
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if even number of observations exists, the median is the mean of the two middle values
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Factors of Median
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- 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 |
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Sample Mode
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Data value that occurs the most; may not be in the center (aka crude mode or model class)
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Unimodel
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1 Mode
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Bimodel
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1 Modes
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Multimodel
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several Modes
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No Mode
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data values only occur once
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Factors of MODE
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- most frequent value is saught
- simplest "average" to find - can be used for group categorical data - isn't always unique |
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Sample Mid-Range
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sum of smallest and largest data value divided by 2
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Factors od MIDRANGE
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- not resistant to outliers
- easy to compute - uses only 2 data values - less efficient to the mean |
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Symmetrical Distribution
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all values of average (mean, median, mode) are the same value
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Skewed Distribution
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the mean shifts toward the direction of the skew (right and left skew)
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Positive Skew
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Right Skew; most common; mean to the right and is therefor larger then the median and mode (Mode, Median, then Mean)
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Negative Skew
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Left Skew; Mean is to the left (Mean, Median, then Mode)
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Sample Mean Formula
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write formula:
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Population Mean Formula
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write formula:
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Left Skewed
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Draw Skew
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Right Skewed
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Draw Skew
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Symmetrical Distribution
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Draw scale
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