Videos: Part 1. Using Test Information II

This multimedia segment, Part 1. Introducing Continuous Test Results, includes three videos. In addition to the videos, materials include an instructor's note, companion slides, a glossary, an annotated bibliography, and sample exercises.

Access the videos.

• Video 1.1 Continuous test results (~11 min)
• This video reviews continuous test results by plotting the distribution of test results among diseased and non-diseased patients. It shows that a cutoff can be chosen to dichotomize test results which influences the magnitude of the false negatives and the false positives and the true positives and the true negatives.
• Video 1.2 Changing cutoff points (~13 min)
  This video demonstrates the implications of changing the cutoff, above which we call a test positive, and below which we call a test negative. The receiver operating characteristic (ROC) curve is introduced as a way to illustrate the relationship between the true-positive rate and the false-positive rate for different cutoff points.
• Video 1.3 Deriving the optimal positivity criterion (~14 min)
  This video shows how the formula to calculate an optimal positivity criterion can be derived using a decision tree format.

Multimedia segment Part 1. Introducing Continuous Test Results (Videos 1.1, 1.2, 1.3) should be followed by Part 2. Optimal Positivity Criterion - Iron Deficiency Example (Videos 2.1, 2.2, 2.3, 2.4).

This teaching pack was developed by Sue J. Goldie at the Center for Health Decision Science, Harvard T.H. Chan School of Public Health. The multimedia components were developed as part of a series of pilots in the CHDS Media Hub, led by Jake Waxman, where media-based pedagogy experiments contribute to new ways of thinking about short form content.