Descriptive Statistics2

Descriptive Statistics2 - 100%. Interquartile range: values...

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1 Descriptive Statistics 2 4/4/2011 Announcements Chapter 11 HW due Friday Bring calculators from now on Or, with regard to the level of measurement Nominal Data: Mode Ordinal Data: Mode, Median Interval/Ratio Data: Mode, Median, Mean Dispersion How much variation occurs across the data. For nominal data: Eyeball method Frequency distribution Measures of Dispersion Only use with ordinal or higher data Range Quantiles Standard Deviation Variance Range Minimum Maximum Range is maximum minus minimum Problem: doesn’t tell you much about what’s inside
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2 Quantiles Helps understand the inside of a distribution Percentiles = Percentage below a certain value. Other Quantiles Quartile: Four cuts of the data: 25%, 50%, 75%, 100%. Quintile: Five cuts of the data: 20%, 40%, 60%, 80%,
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Unformatted text preview: 100%. Interquartile range: values between 25% and 75%. Types of Graphical Distributions Histogram Similar to bar chart Bins: categories that values may fall in. Scatter plot Instead of bars, dots show frequency falling in each category Scatter plot with smoothed lines Give us a frequency curve Other measures of dispersal Mean deviation Average distance of observations from mean. Standard Deviation and Variance Measures of dispersion around the mean. Bell shaped Unimodal: one peak Symmetrically falls off on either side of peak Mean, median, and mode in same place! Skewness How asymmetrical is the distribution? Positive skew 3 Negative skew Kurtosis Measure of peakedness...
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This note was uploaded on 06/06/2011 for the course POLI 301 taught by Professor Mcatee during the Spring '11 term at South Carolina.

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Descriptive Statistics2 - 100%. Interquartile range: values...

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