The number of minutes each of 26 students in a class spent to complete an obstacle course is shown below. 5,2,5,5,8,12,6,7,5,5,6,5,5,5,6,10,7,5,5,7,5,7,5,7,6,6 a. Identify any outliers in the data. Use your calculator. minX = 2 Q 1 = 5 med = 5.5 Q 3 = 7 maxX = 12 Warm-Up 5/07

Rigor: You will learn how to classify study types and design statistical studies. Relevance: You will be able to design real world surveys and an experiments.

011-1 Designing a Study

A Parameter is a population characteristic. A statistic is a measure calculated by using data of a sample of the population. An unbiased sample is important to obtain good information and draw accurate conclusions. A bias is an error that results in a misrepresentation of members of a population. A random sample in which members of the population are selected entirely by chance. Identify the objective of the study. Choose a sample, and collect data. Organize the data and calculate sample statistics. Make, inferences, and draw conclusions about the population

Key Concept: Study Types Survey: Data is collected from responses given by members of a population. Experiment: A sample is divided into two groups, an experimental group and a control group. Then the groups are compared. Observational study: Members of a sample are measured or observed without being affected by the study.

Example 1: Determine whether each 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.A record label wants to test three designs for an album cover. They randomly select 50 teenagers from local high schools to view the covers while they watch and record their results. b.The city council wants to start a recycling program. They send out a questionnaire to 200 random citizens asking what items they would recycle. Observational study Sample is the 50 teenagers. Population is all potential purchasers of the album. Survey Sample is the 200 random citizens. Population is all of the citizens of the city.

Example 2: Determine whether each situation calls for a survey, an experiment, or an observational study. Explain your reasoning. a.A pharmaceutical company wants to test whether a new medicine is effective. b.A news organization wants to randomly call citizens to gauge opinions on a presidential election. ExperimentThe drug will need to be tested on a sample group. Survey Members of a sample population will be asked questions.

Design a Survey Step 1: Clearly state the objectives Step 2: Identify the population Step 3: Write unbiased survey questions. Avoid survey questions that: are confusing or wordy encourage a certain response cause a strong reaction address more than one issue

Example 3: Determine whether each survey question is biased or unbiased. Explain your reasoning. a.Don’t you agree that the cafeteria should serve healthier food? b.How often do you exercise? BiasedIt encourages a certain response. Unbiased It is clearly stated and does not encourage a certain response.

Example 4 Design a Survey: Jim is writing an article for his school newspaper about online courses. He wants to conduct a survey to determine how many students at his school would be interested in taking an online course from home. State the objective of the survey, suggest a population, and write two unbiased survey questions. Step 1: Clearly state the objectives Step 2: Identify the population Step 3: Write unbiased survey questions. The objective is to determine students’ interest in taking an online course from home. The population is the student body. Do you have a computer? If offered, would you take an online course?

Design an Experiment Step 1: Clearly state the objectives Step 2: Identify the population. Step 3: Determine the experimental and control groups. Step 4: Define the sample procedure.

Example 5: Identify any flaws in the design of the experiment, and describe how they could be corrected. Experiment: An electronics company wants to test whether using a new graphing calculator increases students’ test scores. A random sample is taken. Calculus students in the experiment group are given the new calculator to use, and Algebra 2 students’ in the control group are asked to use their own calculator. Results: When given the same test, the experimental group scored higher than the control group. The company concludes that the use of this calculator increases test scores. The flaw is that the experimental group consist of Calculus students while the control group consist of Algebra 2 students. This could be corrected by selecting all Algebra 2 students.

Example 6 Design an Experiment: A research company wants to test the claims of a plant food that they get “Taller tomato plants in just 3 weeks!”. State the objective of the experiment, suggest a population, determine the experimental and control groups and describe a sample procedure. Step 1: Clearly state the objectives Step 2: Identify the population Step 3: Determine the experimental and control groups. Step 4: Define the sample procedure. The objective is to determine whether tomato plants given the plant food grow taller than tomato plants not given the plant food. The population is all tomato plants. The experimental group is tomato plants given the plant food and the control group is the tomato plants not given the plant food. Measure the heights of plants in each group and give the experimental group the plant food. In 3 weeks measure again and compare results.

Assignment Prob/Stats # WS p271, 1-7 all and p272, 1-7 all