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28 Cards in this Set
- Front
- Back
- 3rd side (hint)
Stemplot
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A quick picture of the shape of a distribution while including the actual numerical values.
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Distribution
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c
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Bar graph
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b
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Histogram
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breaks a variable into classes and displays a count or percentage of each class
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Frequencies
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counts of individuals in each class for a given variable
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Shape
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measure of how a distribution rises and drops
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Ex. The distribution has a roughly symmetric shape.
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Center
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measure of central tendency using mean, median, or mode
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Ex. The distribution has a median of 204
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Spread
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measure of variability; we can use range, interquartile range(Q3-Q1), variance, and standard deviation to calculate the spread of a distribution
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Ex. The distribution has a range of 100 to 900
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Deviations
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Values in any graph of data that do not fit in the overall pattern.
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Symmetric
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A distribution is symmetric if values smaller and larger than its midpoint are mirror images of eachother.
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Skewed
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A distribution is skewed if both sides are not equal. It is skewed right if the "right tail" (larger values) is much longer than the "left tail" (smaller values)
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Quartiles
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r
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First quartile
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s
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Third quartile
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t
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Variance (s^2)
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the average of the squares of the deviation of a set of observations from their mean
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Standard deviation (s)
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square root of the variance and is a measure of spread about the mean
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Resistant
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obtained by using the sample quantiles (percentiles/fractiles). Quantiles are constructed by sorting (ranking) the data into ascending order to obtain a sequence of order statistics.
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the median is a resistant measure of center because its unaffected by extreme observations.
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Linear transformations
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changes the original variable x into the new variable (xnew) given by an equation of the form
xnew = a + bx |
addding the constant "a" shifts all values of x up or down by the same amnt. Multiplying by the positive constant "b" changes the size of the unit of measurement
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Back-to-back stem plot
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Stem plot: quick picture of the shape of a distribution while including the actual numerical values in the graph.
Back-to-back: Used to compare two related distributions. Leaves on each side are ordered out from the common stem. |
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Side-to-side box plot
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A graph of the five-number summary. Because boxplots show less detail than histograms or stemplots, they are best used for side-by-side comparison of more than one distribution.
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Five-Number Summary
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Smallest observation (Minimum), first quartile (Q1), median (M), third quartile (Q3), largest observation (Maximum)
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Boxplot
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Mode
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the value in a data set that appears the most frequently.
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X {3,4,5,5,5,6,6,7,8)
Mode is 5, because it appears the most |
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Pie Chart
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A graphical representation of categorical data in a circle divided into fractions.
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Outlier
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An individual in the data set that does not follow the pattern of the graph of the rest of the data points.
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Ojive
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An Ojive is a relative cumulative frequency graph. It gives us the information about the relative standing of an individual observation.
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Steps:
1. Decide on intervals and make a frequency table (with three columns- relative frequency, cumulative frequency, and relative cumulative frequency). 2. Label and scale axes and title graph. 3. Plot point corresponding with the relative cumulative frequency in each class interval. |
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Time Plot
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Plots each observation against the time at which it was measured.
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Time is on horizontal axis and measured variable is on the vertical axis. Connect the data point to clearly see change over time.
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Trends
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When a series of measurements of a process are treated as a time series, trend estimation can be used to make and justify statements about tendencies in the data, by relating the measurements to the times at which they occurred.
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