University of California, Los Angeles STATS 10 Introduction to Statistical Reasoning Homework #8

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University of California, Los Angeles STATS 10 Introduction to Statistical Reasoning Homework #8 7.1: Parameter vs. Statistics (Example 1) Explain the difference between a parameter and a statist... ic. Parameter: - Based on the units of the population - Specifies on the characteristics of the population Statistic: - Is a statistical measure that calculates the basis of sample observations - Specifies the characteristics of a sample 7.2: Sample vs. Census Explain the difference between a sample and a census. Every 10 years, the U.S. Census Bureau takes a census. What does that mean? A census for the purpose of including every member of the population. A sample is selected based on the interest of the population and is composed of a group of objects. Every 10 years, the U.S. Census Bureau takes a census for the purpose of determining representational apportionment. 7.3: Two symbols are used for the mean: U and x a. Which represents a parameter and which a statistic? A parameter is represented using a u Statistics are represented using a x(dash on the top of the x). b. In determining the mean age of all students at your school, you survey 30 students and find the mean of their ages. Is this mean x or u? The mean would be considered x(dash on the top of the x). 7.4: xvs The mean GPA of all 5000 students at Uneeda College is 2.78. A sample of 50 GPAs from this school has a mean of 2.93. Which number is u and which is x? U is 2.78 X- would be 2.93 7.5: Ages of Presidents Suppose you knew the age at inauguration of all the past U.S. presidents. Could you use those data to make inferences about ages of past presidents? Why or why not? You could not use this data to make inferences about ages of past presidents because there is not a sample from the population. 7.6: Heights of Basketball Team Suppose you find all the heights of the members of the men’s basketball team at your school. Could you use those data to make inferences about heights of all men at your school? Why or why not? This data cannot be used to make inferences about heights of all men at your school because the sample has only considered the heights of the men in the basketball team. 7.7: Sample vs. Census You are receiving a large shipment of batteries and want to test their lifetimes. Explain why you would want to test a sample of batteries rather than the entire population. I would want to test a sample of batteries rather than the entire population because if I were to do the entire population it takes a lot of time and is too expensive. 7.8: Sampling GPAs Suppose you want to estimate the mean GPA of all students at your school. You set up a table in the library asking volunteers to tell you their GPAs. Do you think you would get a representative sample? Why or why not? No you would not get a representative sample. You wouldn’t get one because it is not a random sample (the responses you recieve are voluntary). 7.15: Questionnaire Response (Example 3) A teacher at a community college sent out questionnaires to evaluate how well the administrators were doing their jobs. All teachers received questionnaires, but only 10% returned them. Most of the returned questionnaires contained negative comments about the administrators. Explain how an administrator could dismiss the negative findings of the report. In order to be able to dismiss the negative findings of the report, the administrator would have to get the rest of the 90% of teachers to respond. [Show More]

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