Analysis of One Quantitative Variable, part 2, 215 R Project

This video covers Part 2 of the STA 215 R Project: Analysis of One Quantitative Variable, with a focus on comparing a quantitative variable across groups using the gvsu215 package.

In this video, students learn how to extend single-variable analysis to a grouped context by producing numerical summaries and visualizations that support meaningful comparison between groups. The emphasis is on interpreting differences in center, spread, and distribution shape, rather than simply generating output.

Specifically, this video demonstrates how to:

Create numerical summaries of a quantitative variable by group using
tbl_num_sum(DATANAME, VARIABLE ~ BYGROUP, na_rm = TRUE)
and interpret how measures of center and variability differ across groups.

Construct side-by-side boxplots with
plot_box(DATANAME, VARIABLE ~ BYGROUP)
to visually compare distributions, identify differences in spread, skewness, and potential outliers.

Combine numerical summaries and histograms for a single variable using
tbl_num_sum(DATANAME, ~VARIABLE, na_rm = TRUE)
and
plot_hist(DATANAME, ~VARIABLE)
to reinforce how graphical and numerical summaries work together.

Create grouped histograms with
plot_hist(DATANAME, ~VARIABLE, group = ~BYGROUP)
alongside grouped numerical summaries to compare distribution shapes across categories.

Throughout the video, attention is given to how these outputs should be described in clear, statistical language for a project write-up, including how to reference the grouping variable, define the population being compared, and avoid common interpretation errors. This video is designed to support independent project work and reinforce expectations for explanation and reasoning in STA 215.