Week 9

Overview

Learning Goals

• Understand Marginal Effects Estimation

NoteMarginal Effects Mixing Board

You can play with an interactive mixing board using the Palmer penguins dataset at: https://model-mixing-board.surge.sh. See it it helps build your intuitions!

Slides

TipSlides Mon March 02

Readings

• Interactions in Logit Regressions: Why positive may mean negative
• The logic of emmeans (R library)
• From model to meaning with marginaleffects (R library)
• Marginalia: What the heck are marginal effects
• Guide to Effect Sizes & Confidence Intervals
• bossanova documentation

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Updating Assignments More Easily

These instructions are also on classroom guide page

1. Check for the update

Open a terminal, cd into your assignment folder, and run:

gh pr list

If you see a PR titled “GitHub Classroom: Sync Assignment”, continue below.

2. Fetch and merge the update

git fetch origin
git merge origin/psyc-201/main

If the merge completes with no errors, skip to Step 4.

If you see CONFLICT, continue to Step 3.

3. Resolve conflicts in VS Code

git merge will tell you which files have conflicts. First, make sure VS Code is configured as your merge tool (you only need to do this once):

VSCODE="/Applications/Visual Studio Code.app/Contents/Resources/app/bin/code"
git config merge.tool vscode
git config mergetool.vscode.cmd "$VSCODE --wait --merge \$REMOTE \$LOCAL \$BASE \$MERGED"
git config mergetool.keepBackup false

Then run this to open each conflicted file in VS Code’s merge editor:

git mergetool

For each file, VS Code will open a 3-panel merge editor. The key terms to know:

• Current (also called “ours” or “local”) = the version on your branch, i.e. your work
• Incoming (also called “theirs” or “remote”) = the version being merged in, i.e. instructor updates

For each conflicting section, click Accept Current to keep your version or Accept Incoming to take the instructor’s version. The bottom panel shows the result of your choices. When you’re happy with it, click Complete Merge (bottom-right) to finish that file.

git mergetool will automatically move to the next conflicted file until all are resolved. Then commit the merge:

git commit -m "Merge instructor updates"

4. Push and re-setup

git push
uv sync
uv run poe setup

The PR on GitHub will automatically close after you push. If everything worked you should see the new/updated files in your local folder, and you can hack on them as you normally would.