Informal Analysis

Prof Randi Garcia
February 5, 2018

Reading Free-Write (5 minutes)

  1. Explain the assembly line metaphor for how each observation of the response variable is composed. You can think about the enzyme concentrations from Kelly's hamster experiment as the response.
  2. What questions do you have from today's reading? What do you feel fuzzy on?


  • Tim Johnson in class on Wednesday!
  • HW 2 due on Wednesday at 5p (envelope outside of my office)
  • DataFest 2018 information session, Feb 7th, 7-8p
  • Smithies in SDS (SSDS) general info session, Feb 8, 7-8p
  • WiDS at WPI on March 5th


  • Design Principals and four designs
  • Informal analysis

Design Principal 1: Random Assignment

Design 1: Randomized Basic Factorial Design, BF[1]

  • Research question: Is enzyme concentration different bewteen long day and short day hamsters?

Gender Bias in STEM

Randomized Basic Factorial Design BF[1]

In a randomized double-blind study (n = 127), science faculty from research-intensive universities rated the application materials of a student who was randomly assigned either a male or female name for a laboratory manager position. Faculty participants rated the male applicant as significantly more competent and hireable than the (identical) female applicant. These participants also selected a higher starting salary and offered more career mentoring to the male applicant. See materials here

Acid Rain

Randomized Basic Factorial Design BF[1]

“Clean” precipitation has a pH in the 5.0 to 5.5 range, but observed precipitation pH in northern New Hampshire is often in the 3.0 to 4.0 range. Is this acid rain hurting trees? 240 six-week-old yellow birch seedlings were randomly assigned to one of 5 groups. Each group received an acid rain mist at the following pH levels: 4.7, 4.0, 3.3, 3.0, and 2.3. After 17 weeks, the seedling were weight, and their total plant (dry) weight was recorded.

Design Principal 2: Blocking

Design 2: One-Way Complete Block Design, CB[1]

  • Research questions:
    1. Is enzyme concentration different bewteen hearts and brains?
    2. Do hamsters differ in their enzyme concentrations?