STAT 184 Lecture 7: lecture7_week7_part_I
Document Summary
Glyph-ready data often combines data from different sources. Perhaps they come from different experiments or institutions. Often, they were collected with different objectives than yours. Perhaps they are completely different types of data, Medicarecharges: charges and payments for different drgs by different providers. Zipdemography: population and age structure in each zip code. Storing data in separate tables can be beneficial even when the data are coming from the same source: There is no one size fits all glyph-ready format. Often the kinds of analysis that will be done are not specifically anticipated when data are collected. This makes it hard to update or correct data. Strategy: don"t even try to smash all data into one big table. A join is a data verb that combines two tables. These care called the left and the right tables. All involve establishing a correspondence a match between each case in the left table and zero or more cases in the right table.
