chapter8 - Designingexperiments PSLS chapter 8 2009 W. H....

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
    Designing experiments PSLS chapter 8 © 2009 W. H. Freeman and Company
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Objectives (PSLS chapter 8) Designing experiments Experimental terminology Comparing treatments Avoiding bias Types of randomized designs Ethics and experimentation
Background image of page 2
Terminology The individuals in an experiment are the experimental units. If they are human, we call them subjects. The explanatory variables in an experiment are often called factors . A treatment is any specific experimental condition applied to the subjects. If an experiment has several factors, a treatment is a combination of specific values of each factor. The factor may be the administration of a drug. One group of people may be placed on a diet/exercise program for 6 months (treatment), and their blood pressure (response variable) would be compared with that of people who did not diet or exercise.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
If the experiment involves giving two different doses of a drug, we say that we are testing two levels of the factor. A response to a treatment is statistically significant if it is larger than you would expect by chance (due to random variation among the subjects). We will learn how to determine this later. In a study of sickle cell anemia, 150 patients were given the drug hydroxyurea, and 150 were given a placebo (dummy pill). The researchers counted the episodes of pain in each subject. Identify: •The subjects (patients, all 300) •The factors/treatments (hydroxyurea and placebo) •And the response variable (episodes of pain)
Background image of page 4
Comparing treatments Experiments are comparative in nature: We compare the response to a treatment versus to: another treatment no treatment (a control) a placebo or any combination of the above A control is a situation in which no treatment is administered. It serves as a reference mark for an actual treatment (e.g., a group of subjects does not receive any drug or pill of any kind). A
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 10/07/2011 for the course BSTT 400 taught by Professor Sallyfreels during the Fall '11 term at Ill. Chicago.

Page1 / 17

chapter8 - Designingexperiments PSLS chapter 8 2009 W. H....

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online