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  3. HarvardX Data Science Module 4 - Inference and Modeling

Exercise

Exercise 9. Comparing to actual results by pollster - multiple polls

Remake the plot you made for the previous exercise, but only for pollsters that took five or more polls.

You can use dplyr tools group_by and n to group data by a variable of interest and then count the number of observations in the groups. The function filter filters data piped into it by your specified condition.

For example:

data %>% group_by(variable_for_grouping) 
    %>% filter(n() >= 5)

Instructions

100 XP
  • Define a new variable errors that contains the difference between the estimated difference between the proportion of voters and the actual difference on election day, 0.021.
  • Group the data by pollster using the group_by function.
  • Filter the data by pollsters with 5 or more polls.
  • Use ggplot to create the plot of errors by pollster.
  • Add a layer with the function geom_point.