Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb...
Transcript of Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb...
![Page 1: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/1.jpg)
Producing DataSections 8.1, 8.2, 8.3
Lecture 16
Robb T. Koether
Hampden-Sydney College
Wed, Feb 10, 2016
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 1 / 11
![Page 2: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/2.jpg)
Outline
1 Population vs. Sample
2 Bad Sampling Methods
3 Assignment
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 2 / 11
![Page 3: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/3.jpg)
Outline
1 Population vs. Sample
2 Bad Sampling Methods
3 Assignment
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 3 / 11
![Page 4: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/4.jpg)
Population vs. Sample
Definition (Population)In a statistical study, the population is the set of all individuals aboutwhich we want information.
Definition (Sample)Given a population, a sample is a set of individuals in the population,i.e., a subset of the population, from which we obtain information.
It is typically not practical to obtain information from everyindividual in the population.
Why not?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 4 / 11
![Page 5: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/5.jpg)
Population vs. Sample
Definition (Population)In a statistical study, the population is the set of all individuals aboutwhich we want information.
Definition (Sample)Given a population, a sample is a set of individuals in the population,i.e., a subset of the population, from which we obtain information.
It is typically not practical to obtain information from everyindividual in the population.Why not?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 4 / 11
![Page 6: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/6.jpg)
Outline
1 Population vs. Sample
2 Bad Sampling Methods
3 Assignment
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 5 / 11
![Page 7: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/7.jpg)
The Meanding of Random
Definition (Random)A outcome of a procedure is random if it is left entirely to chance.
“Random” is often taken to mean that all outcomes are equallylikely, but that is not what random means.
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 6 / 11
![Page 8: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/8.jpg)
A Bad Sampling Method
Example (A Bad Sampling Method)Suppose I wanted to select a random sample of 4 students from aclass of 20 students.
I start at the beginning of the class roll and toss a coin.Heads, that student is selected.Tails, he is not selected.
I move on to the next student on the roll and use the same rule.I continue in this manner until I have 4 students.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 7 / 11
![Page 9: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/9.jpg)
A Bad Sampling Method
Example (A Bad Sampling Method)Suppose I wanted to select a random sample of 4 students from aclass of 20 students.I start at the beginning of the class roll and toss a coin.
Heads, that student is selected.Tails, he is not selected.
I move on to the next student on the roll and use the same rule.I continue in this manner until I have 4 students.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 7 / 11
![Page 10: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/10.jpg)
A Bad Sampling Method
Example (A Bad Sampling Method)Suppose I wanted to select a random sample of 4 students from aclass of 20 students.I start at the beginning of the class roll and toss a coin.
Heads, that student is selected.Tails, he is not selected.
I move on to the next student on the roll and use the same rule.
I continue in this manner until I have 4 students.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 7 / 11
![Page 11: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/11.jpg)
A Bad Sampling Method
Example (A Bad Sampling Method)Suppose I wanted to select a random sample of 4 students from aclass of 20 students.I start at the beginning of the class roll and toss a coin.
Heads, that student is selected.Tails, he is not selected.
I move on to the next student on the roll and use the same rule.I continue in this manner until I have 4 students.
Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 7 / 11
![Page 12: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/12.jpg)
A Bad Sampling Method
Example (A Bad Sampling Method)Suppose I wanted to select a random sample of 4 students from aclass of 20 students.I start at the beginning of the class roll and toss a coin.
Heads, that student is selected.Tails, he is not selected.
I move on to the next student on the roll and use the same rule.I continue in this manner until I have 4 students.Is the sample a random sample?
Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 7 / 11
![Page 13: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/13.jpg)
A Bad Sampling Method
Example (A Bad Sampling Method)Suppose I wanted to select a random sample of 4 students from aclass of 20 students.I start at the beginning of the class roll and toss a coin.
Heads, that student is selected.Tails, he is not selected.
I move on to the next student on the roll and use the same rule.I continue in this manner until I have 4 students.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 7 / 11
![Page 14: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/14.jpg)
Another Bad Sampling Method
Example (Another Bad Sampling Method)Suppose I wanted to survey a random sample of 25 Farmvilleresidents.
I go to Wal-Mart and stand by the entrance.I select the first 25 individuals who arrive and are willing to besurveyed.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 8 / 11
![Page 15: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/15.jpg)
Another Bad Sampling Method
Example (Another Bad Sampling Method)Suppose I wanted to survey a random sample of 25 Farmvilleresidents.I go to Wal-Mart and stand by the entrance.
I select the first 25 individuals who arrive and are willing to besurveyed.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 8 / 11
![Page 16: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/16.jpg)
Another Bad Sampling Method
Example (Another Bad Sampling Method)Suppose I wanted to survey a random sample of 25 Farmvilleresidents.I go to Wal-Mart and stand by the entrance.I select the first 25 individuals who arrive and are willing to besurveyed.
Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 8 / 11
![Page 17: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/17.jpg)
Another Bad Sampling Method
Example (Another Bad Sampling Method)Suppose I wanted to survey a random sample of 25 Farmvilleresidents.I go to Wal-Mart and stand by the entrance.I select the first 25 individuals who arrive and are willing to besurveyed.Is the sample a random sample?
Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 8 / 11
![Page 18: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/18.jpg)
Another Bad Sampling Method
Example (Another Bad Sampling Method)Suppose I wanted to survey a random sample of 25 Farmvilleresidents.I go to Wal-Mart and stand by the entrance.I select the first 25 individuals who arrive and are willing to besurveyed.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 8 / 11
![Page 19: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/19.jpg)
Yet Another Bad Sampling Method
Example (Yet Another Bad Sampling Method)Suppose I wanted to survey a random sample of visitors to myweb page.
I add link to the web page that invites the visitor to fill out thesurvey.If the visitor fills out the survey, then the responses are stored in adatabase.A week later, I check the data base to get my data.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 9 / 11
![Page 20: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/20.jpg)
Yet Another Bad Sampling Method
Example (Yet Another Bad Sampling Method)Suppose I wanted to survey a random sample of visitors to myweb page.I add link to the web page that invites the visitor to fill out thesurvey.
If the visitor fills out the survey, then the responses are stored in adatabase.A week later, I check the data base to get my data.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 9 / 11
![Page 21: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/21.jpg)
Yet Another Bad Sampling Method
Example (Yet Another Bad Sampling Method)Suppose I wanted to survey a random sample of visitors to myweb page.I add link to the web page that invites the visitor to fill out thesurvey.If the visitor fills out the survey, then the responses are stored in adatabase.
A week later, I check the data base to get my data.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 9 / 11
![Page 22: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/22.jpg)
Yet Another Bad Sampling Method
Example (Yet Another Bad Sampling Method)Suppose I wanted to survey a random sample of visitors to myweb page.I add link to the web page that invites the visitor to fill out thesurvey.If the visitor fills out the survey, then the responses are stored in adatabase.A week later, I check the data base to get my data.
Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 9 / 11
![Page 23: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/23.jpg)
Yet Another Bad Sampling Method
Example (Yet Another Bad Sampling Method)Suppose I wanted to survey a random sample of visitors to myweb page.I add link to the web page that invites the visitor to fill out thesurvey.If the visitor fills out the survey, then the responses are stored in adatabase.A week later, I check the data base to get my data.Is the sample a random sample?
Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 9 / 11
![Page 24: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/24.jpg)
Yet Another Bad Sampling Method
Example (Yet Another Bad Sampling Method)Suppose I wanted to survey a random sample of visitors to myweb page.I add link to the web page that invites the visitor to fill out thesurvey.If the visitor fills out the survey, then the responses are stored in adatabase.A week later, I check the data base to get my data.Is the sample a random sample?Is this a good sampling method?
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 9 / 11
![Page 25: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/25.jpg)
Outline
1 Population vs. Sample
2 Bad Sampling Methods
3 Assignment
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 10 / 11
![Page 26: Producing Data Sections 8.1, 8.2, 8people.hsc.edu/faculty-staff/robbk/math121/lectures... · Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb](https://reader033.fdocuments.us/reader033/viewer/2022050204/5f575b31444afa11f34f9344/html5/thumbnails/26.jpg)
Assignment
AssignmentRead Sections 8.1, 8.2, 8.3.Apply Your Knowledge: 1, 3, 4, 5.Check Your Skills: 17, 18, 20.Exercises 26, 27, 29 (use the TI-83).
Robb T. Koether (Hampden-Sydney College) Producing DataSections 8.1, 8.2, 8.3 Wed, Feb 10, 2016 11 / 11