FAQ: Variance in R - Review

This community-built FAQ covers the “Review” exercise from the lesson “Variance in R”.

Paths and Courses
This exercise can be found in the following Codecademy content:

Learn R

FAQs on the exercise Review

There are currently no frequently asked questions associated with this exercise – that’s where you come in! You can contribute to this section by offering your own questions, answers, or clarifications on this exercise. Ask or answer a question by clicking reply (reply) below.

If you’ve had an “aha” moment about the concepts, formatting, syntax, or anything else with this exercise, consider sharing those insights! Teaching others and answering their questions is one of the best ways to learn and stay sharp.

Join the Discussion. Help a fellow learner on their journey.

Ask or answer a question about this exercise by clicking reply (reply) below!
You can also find further discussion and get answers to your questions over in #get-help.

Agree with a comment or answer? Like (like) to up-vote the contribution!

Need broader help or resources? Head to #get-help and #community:tips-and-resources. If you are wanting feedback or inspiration for a project, check out #project.

Looking for motivation to keep learning? Join our wider discussions in #community

Learn more about how to use this guide.

Found a bug? Report it online, or post in #community:Codecademy-Bug-Reporting

Have a question about your account or billing? Reach out to our customer support team!

None of the above? Find out where to ask other questions here!

I tried recreating the histogram in the explanation paragraph with basic R.
I thought I’d share the code here since it includes a few styling declarations you might find useful (although ggplot seems like such a simpler choice):

hist(teacher_one_grades, 
     col=rgb(70, 130, 180, max = 255, alpha = 215),
     border="white",
     xlim=c(65,105),
     ylim=c(0,7),
     main="Student test grades in two different classes",
     xlab="Grades",
     ylab=NA,
     breaks=10)
hist(teacher_two_grades,
     col=rgb(255, 140, 0, max = 255, alpha = 150),
     border="white",
     add=T,
     breaks=50)
legend("topright", 
       c("Teacher 1 Scores", "Teacher 2 Scores"), 
       col=c(rgb(70, 130, 180, max = 255, alpha = 215), 
             rgb(255, 140, 0, max = 255, alpha = 150)), 
       lwd=5,
       cex=0.75)
box()

The only thing I could not find is how to make the borders of the bars thinner.
Let me know if any of you know how to do that.

Run the code to see two datasets that have a similar mean, but look very different.

I’m only seeing one dataset of the same authors example used throughout the lesson, and no variance value, am I missing something?

4 Likes

Came here to say this, that page is incomplete

1 Like

Yea this page is using the “Mode in R” notebook, instead of an actual review page for “Variance in R”. Would be great to see the two datasets that they talk about in the description but the code seems to not have been carried over with the review text.

This remains incomplete months later. Quite a bit of this course feels incomplete, which is a touch unacceptable.

1 Like