Section 1.4 Other Effective Sampling Methods

A radio station asks its listeners to call in their opinion regarding the form at the format of the morning show. Question content area bottom Part 1 What type of sampling is​ used? A. Stratified B. Cluster C. Simple random D. Systematic E. Convenience

C

Homework question on canvas To determine customer opinion of their pricing​, Amtrak randomly selects 90 trains during a certain week and surveys all passengers on the train Question content area bottom Part 1 What type of sampling is​ used? A. Stratified B. Convenience C. Cluster D. Simple random E. Systematic

C

Homework question on canvas A(n) is obtained by dividing the population into groups and selecting all individuals from within a random sample of the groups what answer above go in the blank?

Cluster sample

1.) A stratified sample is one obtained by separating the population into homogeneous, nonoverlapping groups called strata, and then obtaining a simple random sample from each stratum. The individuals within each stratum should be homogeneous (or similar) in some way. Even if we use random sampling to obtain a representative sample, sometimes as a result of a coincidence we may choose a sample that underrepresents some part of the population. For example, if we randomly choose 10 people to be in our sample, coincidentally, we may end up with 7 males and only 3 females. Stratified sampling is specifically designed to prevent the problem of underrepresentation. Assume that our population is:30% Democrat45% Independent25% Republican And suppose we want a sample of n=200 that Has the exact same proportions.

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See Lecture in canvas for the above example and how they are separated into strata Lecture time 1:38

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Question from the Homework A(n) is obtained by dividing the population into homogeneous groups and randomly selecting individuals from each group simple random sampling, stratified sampling, Cluster convenience sample

stratified sampling

Homework question example Which sampling method does not require a​ frame? Question content area bottom Part 1 Choose the correct answer below. A. Systematic B. Cluster C. Simple random D. Stratified E. All of the above sampling methods require a frame

A

Homework question on canvas Determine whether the following statement is true or false. Explain. Inferences based on voluntary response samples are generally not reliable. Question content area bottom Part 1 Choose the correct answer below. A. ​True, because it is often the case that the individuals who volunteer do not accurately represent the population. B. ​True, because the group that volunteers may not be a large enough sample size. C. ​False, because individuals who volunteer are least likely to have personal bias. D. ​False, because a surveyor cannot force volunteers to respond.

A

lecture slide 3 lecture time 0:27 Assume that our population is: 30% Democrat 45% Independent 25% Republican And suppose we want a sample of n=200 that Has the exact same proportions.

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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 Party 2 Bolden Nolan Cooper Ochs Carter Pawlak Engler Rice Haydra Tate Keating Thomas Lukens Wright May Weber Which of the following is a possible list of club members to lead the panel​ discussion? A. Pawlak​,Tate​, Cooper​, May B. Cooper​, May​, Thomas​, Pawlak

A

A sales person obtained a systematic sample of size 25 from a list of 500 clients. To do​ so, he randomly selected a number from 1 to 20​, obtaining the number 12. He included in the sample the 12th client on the list and every 20th client thereafter. List the numbers that correspond to the 25 clients selected. Question content area bottom Part 1 Choose the correct answer below. A. 12​, 32​,..., 492 B. 20​, 32​,..., 308 C. 25​, 45​,​..., 500 D. 12​, 32​,​..., 487

A

Homework question from canvas Ford wants to administer a satisfaction survey to its current customers. Using their customer​ database, the company randomly selects 4040 customers and asks them about their level of satisfaction with the company. Question content area bottom Part 1 What type of sampling is​ used? A. Stratified B. Simple random C. Cluster D. Convenience E. Systematic

B

Homework question on canvas 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. Question content area bottom Part 1 Choose the correct answer below. A. ​False, because simple random samples require a larger sample size than most other sampling methods. B. ​True, because every individual has an equal chance of selection. C. ​True, because it does not require extra preparation and can return more information than the other sampling techniques. D. ​False, because other sampling techniques may provide more information for less cost than a simple random sample.

D

homework question from canvas To estimate the percentage of defects in a recent manufacturing​ batch, a quality control manager at Sony selects every 15th music CD music CD that comes off the assembly line starting with the third until she obtains a sample of 60 music CDs . Question content area bottom Part 1 What type of sampling is​ used? A. Stratified B. Convenience C. Systematic D. Cluster E. Simple random

c

An advantage of stratified sampling over simple random sampling is that it may allow fewer individuals to be surveyed while obtaining the same or more information

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In Lecture on canvas time 0:23 Even if we use random sampling to obtain a representative sample, sometimes as a result of a coincidence we may choose a sample that underrepresents some part of the population. For example, if we randomly choose 10 people to be in our sample, coincidentally, we may end up with 7 males and only 3 females. Stratified sampling is specifically designed to prevent the problem of underrepresentation.

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