Please complete before the next class.

Make sure that you’ve completed all previous HW first.


I extended the due date for the textbook and calculator selfie on Canvas. It’s now due Saturday night. This exercise is worth one point.

Causal Inference

Read and review your notes and my slides over causality and causal inference. Answer the following questions:

  1. Describe the four ways to obtain a correlation.
  2. Describe the other, fifth way you can get a correlation (i.e., by tricking yourself).
  3. I write that, under randomization, \(R^{obs}_T - R^{obs}_C \approx R^{hyp}_T - R^{hyp}_C\).
    1. What do each of these four quantities refer to? What do we call the left-hand side? The right-hand side?
    2. Notice that the equality is not exact. Instead, it is approximate. What is the only reason it is not exact.
    3. Explain why randomization allows us to rule out spuriousness and reverse causation.
    4. Describe the design of Gerber and Green’s turnout experiment. Describe the results (i.e., what percent of each group voted?). Discuss whether and how you can rule out any of the four possible ways to obtain a correlation.
  4. Was Gerber, Green, and Larimer’s study ethical? For 1/2 point extra credit, answer the discussion question on our Canvas discussion board.


Read chs. 1 and 2 of FPP (the textbook; see the syllabus) and do the assigned review exercises here.

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Carlisle Rainey