Lecture 16: Data Scales and Summary Statistics

Overview of data scales — categorical/nominal; ordinal; interval; ratio — and what can and can’t be done with each.

The notion of statistic as a value that reports some property of data. Some commonly used summary statistics: mode, median, mean, variance, standard deviation. The difference between statistics for a complete population, and for a sample drawn from that population. Using statistics from a small random sample to estimate the statistics of a large population.

Exercise

See what value you get for (1.2-1.0==0.2) on your calculator, and in some different programming languages. Then don’t compare floating-point values for equality ever again.

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