How old are we?



Grayson White

Stat 243
Week 1 | Fall 2026

Goals for Today (and next time)

Today:

  • Guess the age of Reed math / stats / cs faculty
  • Start to think about quantifying error

Friday (lab):

  • Technologies, Data, and Stat Learning Methods

Before we get started: Pre-lab assignment

Before Thursday 9/3 (tomorrow) at noon, please do the following:



We’ll use GitHub for our class, so each of you need to have a GitHub profile. If you don’t have a GitHub profile already, go to https://github.com/ and sign up for one. Once you’ve signed up for an account, please add it to the Google Sheet so that I can add you to the stat-243-f26 organization. Note: you’ll need to be logged in to your Reed Google account to edit the Google Sheet.

How Old Are We?

The Rules

I will display photos from 8 current and former math/stats faculty:

  • Goal: Estimate the age of each faculty member (at the time the picture was taken)
  • Note: None of these pictures were taken this year!

Work in groups of 2-3 to develop a consistent method for estimating age.

Record your estimates for each faculty member on paper and submit it to me.

Photo 1

Photo 2

Photo 3

Photo 4

Photo 5

Photo 6

Photo 7

Photo 8

All Photos

As we wait for groups to guess ages, complete the reflection worksheet.

Questions

Reflection: Modeling Questions

  • What explicit features are you analyzing?
  • How do you convert these features to numerical estimates?
  • How do you resolve differences in opinion among group members?

Reflection: Definitional Questions

  • Is the activity supervised or unsupervised?
    • Supervised
  • Does it represent a classification or regression problem?
    • Regression
  • Are you interested primarily in prediction or inference?
    • Prediction
  • Are you using parametric or non-parametric methods?
    • Either would have worked!

Reflection: Conceptual Questions

  • What are some sources of “error” in your estimates?
  • How can we quantify the error in your estimates?
  • How should we assess the overall accuracy of a group’s predictions?
  • In what other circumstances do people (or companies, or algorithms) predict age based on photos or physical appearance? Is that ethical?

Results

(on the board)

Returning to conceptual questions

  • What are some sources of “error” in your estimates?
  • How can we quantify the error in your estimates?
  • How should we assess the overall accuracy of a group’s predictions?
  • In what other circumstances do people (or companies, or algorithms) predict age based on photos or physical appearance? Is that ethical?

Next Time

  • Lab 1: Technologies, Data, and Stat Learning Methods
  • Remember, before Thursday 9/3 (tomorrow) at noon, please do the following:

We’ll use GitHub for our class, so each of you need to have a GitHub profile. If you don’t have a GitHub profile already, go to https://github.com/ and sign up for one. Once you’ve signed up for an account, please add it to the Google Sheet so that I can add you to the stat-243-f26 organization. Note: you’ll need to be logged in to your Reed Google account to edit the Google Sheet.