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 * Aim:** How do we design an unbiased study?

At the end of the lesson, you will be able to...
 * 1) distinguish among the different kinds of studies (survey, observation, controlled experiment)
 * 2) determine the factors that may affect the outcome of each type of survey
 * 3) from given descriptions of surveys explain why they fit the model of a specific type of study
 * 4) explain the meaning of population and sample
 * 5) tell whether a given method of data collection uses population or a sample
 * 6) given a variety of situations, determine which type of data collection should be used

For this lesson you will need to define the following terms as they relate to statistics... survey, observation, controlled experiment, census, population and sample


 * How is a population different than a sample?
 * How is a census related to a population and a sample?


 * In order for a sample to relfect the properties of a whole group, the following conditions should exist for it to be** //unbiased**//

Example 1: A new medicine intended for use by adults is being tested on five men whose ages are 22, 24, 25, 27, and 30. Does the sample provide a valid test? Explain why.

Example 2: The management of a health club has received complaints about the temperature of the water in the swimming pool. They want to sample 50 of the 200 members of the club to determine if the temperature of the pool should be changed. How should this sample be chosen?

In the next problems, suggest a method that might be used to collect data for each study. Tell whether your method uses a population or sample.
 * 1) Average temperature for each month for a given city
 * 2) Customer satisfaction at a restaurant
 * 3) Temperature of a patient in a hospital over a period of time
 * 4) Grades for students on a test
 * 5) Population of each of the states of the United States
 * 6) Heights of children entering kindergarten
 * 7) Popularity of a new movie


 * Homework:** Answer each of the following...


 * 1) In a controlled experiment, tow groups are formed to determine the effectiveness of a new cold remedy. One group takes the medicine and the other takes a placebo (a harmless liquid that does nothing). Explain why two groups are necessary. Explain why it is necessary that a participant does not know to which group he or she belongs.
 * 2) Suppose you are in charge of planning the senior trip. The choices are a baseball fantasy camp, Colonial Williamsburg, or Disney World. for each of these choices, explain how you would design a study that would be **BIASED** so that it would lead people to believe that most of the seniors want to go on tt particular trip.
 * 3) A group of eight students decided that they wanted to lose weight. Four of them decided to walk a mile each day before school. The other four of them decided to walk a mile each day after school. All eight weigh themselves each Wednesday and report their weight to their math teacher, who is keeping it confidential. One student in the class says this is an experiment. A second student says disagrees and says this is an observational study. A third student thinks this is just a survey. Write a paragraph why you believe the study is an experiment, an observational study, or a survey. Be clear and concise.