Introduction

Content

  • Syllabus and learning objectives
  • Review
    • Population and samples
    • Observational versus experimental studies
    • Sampling schemes: random, stratified and cluster sampling
  • Introduction to experimental designs
  • Terminology of experimental design
  • Requirements for a good experiment

Learning objectives

  • Learning the terminology associated to experiments.
  • Assessing the generalizability of a study based on the consideration of the sample characteristics, sampling scheme and population.
  • Distinguishing between observational and experimental studies.
  • Understanding the rationale behind the requirements for good experimental studies.

Preliminaries

Readings

Warning

These readings should be completed before class, to ensure timely understanding and let us discuss the concepts together through various examples and case studies — the strict minimum being the course notes. If you feel a section is redundant and overlaps with the latter, feel free to skim through the rest of the material.

Feel free to inform me in the weekly check-in of your take on these references.

Complementary readings

Warning

Complementary readings are additional sources of information that are not required readings, but may be useful substitutes. Sometimes, they go beyond the scope of what we cover (in more details).

  • Chapter 1 (Preliminaries) in Planning of experiments (Cox, 1958). Out of print, but addresses the basic concepts using a variety of examples (mostly from agricultural field trials), and particularly well written.
  • Chapter 1 and Sections 2.1-2.2 in Design and Analysis of Experiments (Dean et al., 2017)

Slides

The slides for today’s lesson are available online as an HTML file. Use the buttons below to open the slides either as an interactive website or as a static PDF (for printing or storing for later). You can also click in the slides below and navigate through them with your left and right arrow keys.

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Tip

Fun fact: If you type ? (or shift + /) while going through the slides, you can see a list of slide-specific commands.

Case study

We will discuss the summary of Abaluck et al. (2022) “The Impact of Mask Distribution and Promotion on Mask Uptake and COVID-19 in Bangladesh” (pdf) in class.

During the activity, you will be asked to identify in teams the following:

  • the objective of the study
  • the target population (which findings generalize?)
  • the sampling scheme
  • the observational and experimental units
  • the treatments
  • the outcome variable(s)

References

Abaluck, J., Kwong, L. H., Styczynski, A., Haque, A., Kabir, Md. A., Bates-Jefferys, E., Crawford, E., Benjamin-Chung, J., Raihan, S., Rahman, S., Benhachmi, S., Bintee, N. Z., Winch, P. J., Hossain, M., Reza, H. M., Jaber, A. A., Momen, S. G., Rahman, A., Banti, F. L., … Mobarak, A. M. (2022). Impact of community masking on COVID-19: A cluster-randomized trial in Bangladesh. Science, 375(6577). https://doi.org/10.1126/science.abi9069
Cox, D. R. (1958). Planning of experiments. Wiley.
Dean, A., Voss, D., & Draguljić, D. (2017). Design and analysis of experiments. Springer. https://www.springer.com/gp/book/9783319522487