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 standard deviation of the variable 'gdpPercap' for 1992?
What is the standard deviation of the variable 'gdpPercap' for 1992?
The standard deviation of the variable 'gdpPercap' for 1992#=# #9032#
First, create a subset with only data of 1992:
Alternatively, you can do this also in one line by selecting all the rows in which the year is 1992 and selecting the column 'gdpPercap'. Apply
First, create a subset with only data of 1992:
G1992 <- G[G$year == 1992,]Then apply the function for standard deviation on the variable gdpPercap.
sd(G1992$gdpPercap)
Alternatively, you can do this also in one line by selecting all the rows in which the year is 1992 and selecting the column 'gdpPercap'. Apply
sd() to this selection. sd(G[G$year == 1992, 'gdpPercap'])
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