# Math 145

## Math 145

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##### Presentation Transcript

1. Math 145 January 24, 2007

2. Descriptive Statistics • Individuals – are the objects described by a set of data. Individuals may be people, but they may also be animals or things. • Variable – a characteristic of an individual. A variable can take different values for different individuals. • Qualitative (Categorical) variable – places an individual into one of several groups or categories. {Gender, Blood Type} • Quantitative variable – takes numerical values for which arithmetic operations such as adding and averaging make sense. {Height, Income, Time, etc.} • Consider: #1.18 (p. 20), #1.21 (p.21)

3. Quantitative Variables • Discrete Variables – There is a gap between possible values. • Counts (no. of days, no. of people, etc.) • Age in years • Continuous Variables – Variables that can take on values in an interval. • Survival time, amount of rain in a month, distance, etc.

4. Graphical Procedures • Categorical Data • Bar Chart • Pie Chart • Quantitative Data • Histogram • Stem-and-leaf plot (stemplot) • Dotplot • These plots describe the Distribution of a variable.

5. Length of Stay