1. Descriptive Statistics: Practical 1
Measures of Spread
Measures of Spread
The most frequently used measure for the spread is the standard deviation (or it's square: the variance). In R the commands to calculate these statistics are sd() and var(). You can use these functions the same way as the functions for central tendency.
Use the gapminder data:
What is the variance of the variable 'pop' for 1972?
What is the variance of the variable 'pop' for 1972?
The variance of the variable 'pop' for 1972#=# # 7.858258e+15 #
First, create a subset with only data of 1972:
Alternatively, you can do this also in one line by selecting all the rows in which the year is 1972 and selecting the column 'pop'. Apply
First, create a subset with only data of 1972:
G1972 <- G[G$year == 1972,]Then apply the function for variance on the variable pop.
var(G1972$pop)
Alternatively, you can do this also in one line by selecting all the rows in which the year is 1972 and selecting the column 'pop'. Apply
var() to this selection. var(G[G$year == 1972, 'pop'])
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