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)

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.