Statistics Math 125 - Module 1 Homework 1.4

Determine whether the following statement is true or false. Explain. Inferences based on voluntary response samples are generally not reliable.

True, because it is often the case that the individuals who volunteer do not accurately represent the population.

A magazine asks its readers to call in their opinion regarding the quality of the articles. What type of sampling is​ used?

Convenience

The human resource department at a certain company wants to conduct a survey regarding worker benefits. The department has an alphabetical list of all 3545 employees at the company and wants to conduct a systematic sample of size 30.

(a) What is k​? To find​ k, compute​ N/n and round down.The population is the employees in the​ company, and hence N equals 3545. The desired sample size n is 30. To find k​, we compute N​/n and round down. ​N/n equals 3545​/30 equals 118.2333333 Thus, we take k to be 118. (b) Determine the individuals who will be administered the survey. Randomly select a number from 1 to k. Suppose that we randomly select 6. Starting with the first individual​ selected, the individuals in the survey will be 6​, 124​, 242​..., 3428 NOTE: 6=k 6+k=6+118=124 6+2(11)=6+236=242 6+118(30-1)=6+118(29)=6+3422=3428

Determine whether the following statement is true or false. Explain. A simple random sample is always preferred because it obtains the same information as other sampling plans but requires a smaller sample size.

False, because other sampling techniques may provide more information for less cost than a simple random sample.

Maytag wants to administer a satisfaction survey to its current customers. Using their customer​ database, the company randomly selects 90 customers and asks them about their level of satisfaction with the company. What type of sampling is​ used?

Simple random

To determine her water pressure​, Keri divides up her day into three​ parts: morning,​ afternoon, and evening. She then measures her water pressure at 4 randomly selected times during each part of the day.

Stratified

To estimate the percentage of defects in a recent manufacturing​ batch, a quality control manager at Ford selects every 10th truck that comes off the assembly line starting with the third until she obtains a sample of 110 trucks. What type of sampling is​ used?

Systematic

A pharmaceutical company wants to conduct a survey of 20 individuals who have high cholesterol. The company has obtained a list from primary care physicians throughout the country of 3600 individuals who are known to have high cholesterol. Design a sampling method to obtain the individuals in the sample. Be sure to support the choice.

What sampling​ method(s) is/are​ valid? Select all that apply. Group the individuals by common primary care physician. For each​ group, assign all the individuals different​ numbers, and use a random number table to select an appropriate number of individuals. Alphabetize the list of 10 comma 000 individuals by last name and select one of the first 200 individuals at random. Starting from the selected​ individual, read down the list and select every 200th individual. Group the individuals by common primary care physician. Assign each physician a different number and use a random number table to select physicians until the total number of patients of all the selected physicians is at least 50.

A ___ is obtained by dividing the population into groups and selecting all individuals from within a random sample of the groups.

cluster sample

Suppose a marketing firm wants to gather information about a new product. The firm divided a city into blocks as illustrated.​ (Note: the numbers shown represent house address​ numbers.) Which of the following represents a possible cluster sample of the homes in the​ city?

7480, 7483, 7484, 7487, 7488, 7491, 7492, 7495

To determine customer opinion of their musical variety​, Sony randomly selects 80 concerts during a certain week and surveys all concert goers. What type of sampling is​ used?

Cluster

A club wants to sponsor a panel discussion on an upcoming election. The club wants to have four of its members lead the panel discussion. To be​ fair, however, the panel should consist of two members of each party. Below is a list of members in each party. Obtain a stratified sample of two people from party 1 and two from party 2. Party 1 Bolden Nolan Carter Pawlak Haydra Tate Lukens Wright Party 2 Cooper Ochs Engler Rice Keating Thomas

Which of the following is a possible list of club members to lead the panel​ discussion? Wright​, Carter​, Keating​, Thomas

For a poll of voters regarding a referendum calling for a national renewable energy incentive​, design a sampling method to obtain the individuals in the sample. Be sure to support your choice.

Which sampling method would most likely be used in a poll of voters regarding a referendum calling for a national renewable energy incentive​? Use stratified random sampling. Since this is a national​ issue, different geographical locations are likely to have similar views.

A ___ is obtained by dividing the population into homogeneous groups and randomly selecting individuals from each group.

stratified sample