Statistics chapter 4
displaying quantitative data
Terms
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- mode
- a hump or local high point in the shape of the distribution of a variable is called a "mode". the apparent location of modes can change as the scale of a histogram is changed
- symmetric
- if two halves on either side of the center look approximately alike
- outliers
- outliers are extreme values that don't appear to belong with the rest of the data.
- distribution
- distribution of a variable gives: a. the possible values of the variable | relative frequency of each value
- bimodal
- distributions with two modes
- unimodel
- having one mode. describing the shape of a histogram when it's generally mound-shaped.
- multimodal
- distributions with more than two modes
- timeplot
- displays data the change over time. often values are connected to show trends more clearly
- tails
- parts that typically trail off on either side.
- uniform
- a distribution that is roughly flat
- stem and leaf display
- shows quantitiative data values in a way that sketches the distribution of the data.
- skewed
- if not symmetric and one tail stretches out farther than the other.
- shape
- describe the shape of distribution, look for: a. single vs. multiple modes & b. symmetry vs. skewness
- spread
- a numerical summary of how tightly the values are clustered around the "center"
- dotplot
- graphs a dot for each case against a single axis
- histogram (relative freq.)
- uses adjacent bars to show the distribution of values in a quantitative variable. each bar represents the frequency (or relative freq.) of values falling in an interval of values
- center
- value that attempts the impossible by summarizing the entire distribution with a single number, a "typical" value.