Chapter 11

Be able to perform a simulation using a table of random numbers

Be able to describe a simulation

Remember to use two digits when appropriate (use 01, 02, etc. when a situation requires double digits)

In a simple random sample, any combination of subjects is equally likely to be chosen

Chapter 12

Recognize types of sampling methods (simple random, cluster, stratified, systematic, convenience, voluntary response, multi-stage)

Recognize types of bias (voluntary response bias, nonresponse bias, response bias, undercoverage)

Know the difference between a parameter and a statistic

Chapter 13

Know terms on page 310 & 311 (placebo, blocking, confounding, etc)

Given the details of an experiment, identify the experimental units, factors, treatments, and response variable.

Distinguish between an observational study and an experiment

Design an experiment (with flowchart)

Sam is preparing sweet potato pies as his dessert for Thanksgiving. The store he shops at sells six sweet potatoes in a bag. Based on experience he estimates that there will be no bad sweet potatoes in 40% of the bags, one bad sweet potato in 30% of the bags, and two bad sweet potatoes in the rest. Conduct a simulation to estimate how many bags Sam will have to purchase to have three dozen good sweet potatoes.

Trial 57821 763091 63508 29418

Trial 13026 349932 54636 17877

a) Describe how you will use a random number table to conduct the simulation.

b) Show two trials by clearly labeling the random number table.

a) Use digits 0-3 to represent bags with 6 good sweet potatoes, digits 4-6 to represent bags with 5 good sweet potatoes, and digits 7-9 to represent bags with 4 good sweet potatoes. Use the random number table until the count is 36 good sweet potatoes.

b) Trial 1: purchase 8 bags; Trial 2: purchase 7 bagsIt will take on average 7.5 bags to get at least three dozen good sweet potatoes.

Solution

An article in a local newspaper reported that dogs kept as pets tend to be overweight. Veterinarians say that diet and exercise will help these chubby dogs get in shape. The veterinarians propose two different diets (Diet A and Diet B). Sixty dog owners volunteer to take part in an experiment to help their chubby dogs lose weight. Thirty dogs were large and thirty were small.Diet A: owners control the portions of dog food and dog treatsDiet B: a mixture of fresh vegetables with the dog food and substitute regular treats with baby carrots 1)Identify the subjects 2)Identify the factors and the number of levels for each 3)Identify the response variable 4)Design an experiment to determine whether the diet and

exercise programs are effective in helping dogs to lose weight

1) 60 chubby dogs 2) Diet, 2 levels 3) Weight loss 4)

Answers

60 chubby dogs

Group 1 – Diet A

Group 2 – Diet B

Group 1 – Diet A

Group 2 – Diet B

30 small dogs

30 large dogs

Compare weight loss

Compare weight loss

A polling organization is investigating public opinion about cloning. They phone a random sample of 1200 adults, asking each person one of these questions (randomly chosen):

A.“Do you favor allowing doctors to use cloned cells in attempts to find cures for such terrible diseases as Alzheimer’s, diabetes, and Parkinson’s?”

B.“Should research scientists be allowed to use cloned human embryos in their experiments?”

Which question do you expect will elicit greater support for cloning? What type of bias is this?

Answers

The first question will elicit greater support for cloning. The wording of the question appeals to the emotions of the respondent. The second question conjures up images of scientists experimenting on humans and cloned embryos, and will elicit less support.

This is a form of response bias.