Probability & Sampling

Tracking Progress

Tool Tips and Case Study Presentations

  • Talk about edconnect.
  • Show Canvas quiz.

Supplemental Reading: Probability & Sampling

Write a one sentence definition of probability (without using Google) and share it with me.

Understanding Probability

One dice probability

\[p(x) = \frac{1}{6} \approx 0.1667\]

Sum of two dice probability

What is \(x\) or the event now?

Walmart and probability

Walmart Employees Are Out to Show Its Anti-Theft AI Doesn’t Work

Everseen video: Where do you see probability in their video? Why don’t they say this word?

“Our digital eye has perfect vision and it never needs a day off.”

Walmart Associate Quotes

  • The same person then grabs two gallons of milk by their handles, and moves them across the scanner with one hand. Only one is rung up, but both are put in the bagging area. They then put their own cell phone on top of the machine, and an alert pops up saying they need to wait for assistance—a false positive. “Everseen finally alerts! But does so mistakenly. Oops again,” a caption reads. The filmmaker repeats the same process at two more stores, where they fail to scan a heart-shaped Valentine’s Day chocolate box with a puppy on the front and a Philips Sonicare electric toothbrush. At the end, a caption explains that Everseen failed to stop more than $100 of would-be theft.

Sampling: Walmart and Everseen

  • Was Everseen’s video representative of the retail experience of their product? Did they show a representative sample?
  • Were the Walmart associate examples representative of Everseen’s product?
  • What makes a collection of data a good example or representative of the general product (population)?

Sampling from a Population

You have 150 students that graduated from a major in 2019 and you want to take a sample of 25 of them to estimate starting salaries.

Describe the way you would do each sampling method for the scenario above.

  • Convenience sample
  • simple random sample (SRS)
  • systematic random sample
  • Clustered random sample
  • Stratified random sample

Case Study

  1. One slide should explain what a z-score is and how it is calculated for our graphics.

  2. One slide should show height adjusted z-scores (HAZ) for a few healthy and a few unhealthy children from each gender over all the times using the MAL-ED data.

  3. 1-2 Slides about the health of the children at 365 days (1-year) for multiple countries.

    • One chart should show the distribution of heights for children from at least 4 countries at ~365 days.
    • One chart should have visualizations of the health of the children at ~365 days for each country (height adjusted z-scores).
    • Take the time to explain your concerns about the health of the children of the study based on their z-scores.

  4. One slide should show a plot of the heights of the dutch children over time. Take the time to describe the key takeaways about their growth.