STAT211 Chapter Notes - Chapter 3: Standard Deviation, Average Absolute Deviation, Percentile
26 Jun 2018
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Chapter 3:
Quantitative:
-Takes on a numeric value
-Can be measured
-Quantifies some aspect of an individual or thing
-E.g. (height in cm/in, weight in kgs/lbs, time in sec/hr, etc)
-Plotted using Histograms, Stemplots, Boxplots, and Dot Plots
-Discreet (set values for variables) vs Continuous (variable values are
unlimited)
Qualitative:
-Takes on levels/categories
-Categorical in nature, defining a unit based on what category it falls in
-Also called a categorical variable
-Cannot be measured
-Qualifies some aspect of an individual or thing
-Special case: binary variable (existing in multiple levels)
-E.g. (color, blood type, preference, nationality, etc)
-Displayed using Bar Charts, Pareto Diagrams, and Pie Charts
Frequency: The number of observations in a category.
Relative Frequency: The proportion of observations in a category: relative
frequency = frequency/n where n represents the total number of observations in
a sample.
Percent Relative Frequency: The relative frequency expressed as a percentage:
percent relative frequency = (frequency/n) * 100%
Bar Graph: Illustrates the distribution of a categorical variable: with categories
placed on the x axis and the frequency (or relative or percent frequency) placed
on the y axis.
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Pareto Diagram: A bar graph in which the frequencies are sorted largest to
smallest.
Pie Chart: A chart that displays the relative frequency of each category
represented by the area of the pie segment.
Frequency Table: A table where a quantitative variable into a number of classes
(or bins) and the class boundaries and the frequency of each class is listed.
Cumulative Frequency: The number of observations in that class and any lower
class.
Distribution: What values a variable takes on, and how often it takes on those
values.
Outlier: An observation that falls far from the overall pattern of observations.
Normal Distribution: Distribution that is symmetric, or perfectly bell-shaped on a
histogram.
Unimodel: A distribution with a single peak.
Sample Mean: x = Σx̅i/n
Median: The value that falls in the middle when the data is ordered from smallest
to largest. If n is odd, then the median is the middle value. If n is even, then the
median is the average of the two middle values.
Mode: The most frequently occurring observation.
Median and Mean: If there are more observations lower than the mean, then the
median will be lower than the mean (this is right-skewed); if there are more
find more resources at oneclass.com
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Document Summary
Quantifies some aspect of an individual or thing. E. g. (height in cm/in, weight in kgs/lbs, time in sec/hr, etc) Plotted using histograms, stemplots, boxplots, and dot plots. Discreet (set values for variables) vs continuous (variable values are unlimited) Categorical in nature, defining a unit based on what category it falls in. Qualifies some aspect of an individual or thing. Special case: binary variable (existing in multiple levels) Displayed using bar charts, pareto diagrams, and pie charts. Frequency: the number of observations in a category. Relative frequency: the proportion of observations in a category: relative frequency = frequency/n where n represents the total number of observations in a sample. Percent relative frequency: the relative frequency expressed as a percentage: percent relative frequency = (frequency/n) * 100% Bar graph: illustrates the distribution of a categorical variable: with categories placed on the x axis and the frequency (or relative or percent frequency) placed on the y axis.
