In SOC345/lehmansociology: Tools for Sociology Students Using R

In this template we are going to look at other ways of displaying a single variable visually.

Previously we had looked at Cleveland dot plots. Now let's examine a more traditional bar chart displaying the same information about the number of passengers on each ship.

# Load your libraries here

library('lehmansociology')
library('ggplot2')

Notice we have switched the x and y here.

#type your code here

plot1<-ggplot(ships, aes(x=`Name of Ship` , y=`No. of passengers` ))

# stat="identity" says to use the value from the data set with no other calculations.
plot1 + geom_bar(stat="identity")

What would you say the biggest problems with this graph are?

Do what you can to make the graph better ... You can rotate the x labels by 60 degrees by adding
+ theme(axis.text.x = element_text(angle = 60))

Remember that the + sign goes at the end of the previous line. You can use an angle that is not 60 if you want to.

There are other ways we can display a variable that are different because they do not focus on individual observations. For example we could use a histogram. In that case we need a new plot object that only has an x variable.

plot2<- ggplot(ships, aes(x=`No. of passengers`))

Add geom_histogram() to plot2

If you want, you can try changing the binwith by adding
binwidth=

some number inside the parentheses.
Experiment with that until you find one you like.

Write a few sentences describing the distribution shown in the histogram.

Write a few sentences comparing the bar graph to the histogram.

Now lets add thre vertical lines to the histogram. Those lines will represent the 25th, 50th and 75th percentiles.

Here is the code for the 25th percentile

geom_vline(xintercept=quantile(ships$No. of passengers, probs=c(.25), na.rm=TRUE), color="green", linetype="dashed", size=1)

Remember that you need to add a plus sign at the end of each line except the last one when putting togeher the parts of your graph.

You need to change the code to get the 50th and 75th percentiles.

Also feel free to change the color or size (play around with those).

Box plots

Now let's make a box plot for the same data. Normally box plots are used to compare groups, but in this case we are using just one, so we have to make a fake factor (categorical) variable for the second variable.

To do this add

  x = factor(0)

when creating your plot object (call that plot3)

#Create plot3 with fake factor. 


# Display plot3 using geom_boxplot().

Write a few sentences about the box plot. How does it relate to the histograms?

Pick on nominal( catagorical) variable from the ships data set. Use that as your x variable in the box plot.

Write a few sentences describing the comparisons shown in your box plot.

SOC345/lehmansociology documentation built on May 9, 2019, 11:41 a.m.