Designing a Study 11.1

 Parameter: A measure that describes a characteristic of a population  Statistic: A measure that describes a characteristic of a sample (ie mean, standard deviation)  Bias: An error that results in a misrepresentation of members of a population  Random Sample: A Sample in which every member of the population has an equal chance of being selected. Vocabulary

Study Types

Example 1A Example 1 Determine whether the situation describes a survey, an experiment, or an observational study. Then identify the sample, and suggest a population from which it may have been selected. A retro movie theater wants to determine what genre of movies to play during the next year. They plan to poll 50 random area residents and ask them what their favorite movies are. This is a survey, because the data are collected from participants‘ responses to the poll. The sample is the 50 people area residents that are polled, and the population is all area residents.

Determine whether the situation describes a survey, an experiment, or an observational study. Then identify the sample, and suggest a population from which it may have been selected.  A driving school wants to determine the main issue drivers face while taking the driving test. They watch and record 30 random people taking the test. This is an observational study, because the school is going to observe the drivers without their being affected by the study. The sample is the 30 drivers selected, and the population is all drivers that may take the test. Example 2

 A restaurant manager provides a new entrée to 30 randomly selected tasters and observes their reactions. Determine whether the situation describes a survey, an experiment, or an observational study. Example 3

 Determine whether the survey question is biased or unbiased. If biased, explain your reasoning.  A. Do you think that poisons, such as pesticides, should be sprayed on crops?  B. Are you planning on watching the ultimate sporting event, the Super Bowl? Example 4: Determining Bias

 Identify any flaws in the design of the experiment, and describe how they could be corrected.  Experiment: A research company wants to conduct a study to determine whether a new fishing reel is more effective than the old reel. The experimental procedure consists of using the new reel to catch fish in one lake, and using the old reel to catch fish in another nearby lake that is randomly chosen.  Results: The company concludes that the new reel is twice as effective as the old reel. Example 5: Identifying Flaws

 Experiment A researcher wants to conduct a study to determine the effectiveness of new golf ball. They get 50 players with different playing abilities and compare their scores. They conclude that the new ball is more effective. Example 6: Identifying Flaws

 PETS A research company wants to test a new food for overweight cats that promotes weight loss. State the objective of the experiment, suggest a population, determine the experimental and control groups, and describe a sample procedure. Example 7: Design a Study

 DE-ICERS A research company wants to test a new de-icer for frozen locks. Determine the experimental and control groups, and describe a sample procedure.  A.experimental: a group where the new de-icer is used; control: a group where a different de-icer is used. The performances of the new de-icer and the control de-icer are then compared  B.experimental: a group where a different de-icer is used; control: a group where the new de-icer is used. The performances of the new de-icer and the control de-icer are then compared.  C.experimental: a group where the new de-icer is used; control: a group where a different de-icer is used.  D.experimental: a group where a different de-icer is used; control: a group where the new de-icer is used. Example 8