Progress Check

Check your progress. Use this activity to assess whether you can:

• Describe blinding in an experiment design.

• Explain why blinding is necessary for a given experiment.

Learn by Doing

Use the rubric at the bottom of this page as a guide for completing this assignment.

DIRECTIONS

Submit your work:

• Carefully read all sections below (beginning with the Context section and ending with the Prompt section).

• Commit a good-faith effort to address all items in the Prompt section below. Please be sure to number your responses.

Complete your assigned peer reviews:

• After you submit your initial good-faith attempt, continue to the ANSWER(S) page and review your instructor’s response. But please do not submit your corrected work yet.

• Within three days after the due date, return to this assignment and complete your assigned peer reviews (directions (Links to an external site.)).

Submit your corrected work:

• We all learn from mistakes (our own and our classmates’ mistakes). So please do not immediately correct your own mistakes. If possible, wait until you receive feedback from at least one of your peers.

• If necessary, correct your work and resubmit the entire assignment. Your instructor will only review and grade your most recent submission, so please do not refer to a previous submission.

CONTEXT

A newspaper story in Knight Ridder Newspapers described an experiment in an article with the headline “Doctor Dogs Diagnose Cancer by Sniffing It Out.”

In the experiment researchers trained dogs to identify people with breast or lung cancer. The dogs were trained to lay down if they detected cancer in a breath sample. After the training, dogs sniffed different breath samples of people with and without cancer. Impartial observers watched the dogs and decided when the dog identified a person as having cancer. Researchers then revealed the condition of the person who gave the breath sample and determined if the dog had correctly identified the presence of cancer.

The newspaper states, “The researchers blinded both the dog handlers and the experimental observers to the identity of the breath samples.”

PROMPT

1. Explain what the following sentence means. “The researchers blinded both the dog handlers and the experimental observers to the identity of the breath samples.”

2. Explain why blinding in this experiment is important.