9A Preview

Preparing for the next class

In the next class, you will need to be able to distinguish between a sample and a  population and interpret the mean and standard deviation of a dotplot within the context  of a proportion.

In the next in-class activity, we will build a foundation for statistical inference, which  involves inferring something about a population based on information from a sample.

Definitions

Population: The population is the entire collection of individuals or objects that you  want to learn about.[1]

Sample: A sample is a part of the population that is selected for study.[2]

A researcher is interested in studying adult Swedish women who have osteoporosis. The researcher identifies a random sample of 300 adult women through Sweden’s  universal health system who have been diagnosed with osteoporosis. The researcher  then asks the 300 women whether they would like to be involved in the study.

Question 1

What is the population of interest?

  1. Swedish women
  2. Adult Swedish women with osteoporosis
  3. 300 adult Swedish women with osteoporosis
  4. Swedish women with osteoporosis

Question 2

What is the sample?

  1. Swedish women
  2. Adult Swedish women with osteoporosis
  3. 300 adult Swedish women with osteoporosis
  4. Swedish women with osteoporosis

The main campus of a university in Pennsylvania has a population of about 42,000  students. A survey was administered to a sample of 2,000 students about whether or not they smoke.

Question 3

What is the population of interest?

  1.  42,000 students from the main campus of the university
  2. All students in college
  3. 2,000 students from the main campus of the university
  4. Students from the main campus of the university who smoke

Question 4

What is the sample?

  1. 42,000 students from the main campus of the university
  2. All students in college
  3. 2,000 students from the main campus of the university
  4. Students from the main campus of the university who smoke

Go to the DCMP Describing and Exploring Quantitative Variables tool at  https://dcmathpathways.shinyapps.io/EDA_quantitative/ and create a dotplot of the  energy consumption of Organisation for Economic Co-operation and Development  (OECD) countries using the Energy Consumption of Countries data (you will need to  scroll down when searching for the dataset). Answer the following questions.

Question 5

What is the mean energy consumption of OECD countries?

  1. 36
  2. 195
  3. 120
  4. 125

Question 6

What is the standard deviation of energy consumption of OECD countries?

  1. 57.7
  2. 246
  3. 121
  4. 120

Question 7

What is the correct interpretation of the shape and center of the dotplot?

  1. The shape of the dotplot is unimodal with the center a little below 200 British  thermal units (BTU).
  2. The shape of the dotplot is bimodal with the center around 400 BTU.
  3. The shape of the dotplot is unimodal with the center between 200 and 400 BTU.
  4. The shape of the dotplot is bimodal with the center around 200 BTU.

Question 8

What is the correct interpretation of the variability of the dotplot?

  1. The majority of the values of the dotplot range between 125 and 400 BTU, with  one possible outlier value at 665 BTU.
  2. All of the values of the dotplot are between 125 and 200 BTU.
  3. All of the values of the dotplot are between 200 and 400 BTU.
  4. The majority of the values of the dotplot range between 0 and 125 BTU.

To write in notebook and bring to class: In statistics, when we want to describe the  characteristics of a sample, we call the values statistics. However, when we want to  describe the characteristics of a population, we call those values parameters.

Remember: A statistic describes a characteristic of a sample, and a parameter  describes a characteristic of a population.

  1. Peck, R., Short, T., & Olsen, C. (2019). Statistics: Learning from data, AP edition. Cengage Learning, Inc. ↵
  2. Peck, R., Short, T., & Olsen, C. (2019). Statistics: Learning from data, AP edition. Cengage Learning, Inc. ↵