<< Chapter < Page Chapter >> Page >
This lab incorporate both lab 1 and lab 2 with minitab.

Confidence Interval Lab

Name:

Student learning outcomes:

  • The student will calculate the 90% confidence intervals.
  • The student will interpret confidence intervals.
  • The student will examine the effects that changing conditions has on the confidence interval.
  • The student will examine the relationship between the confidence level and the percent of constructed intervals that contain the population average.

Part i

Collect the data

Check the Real Estate section in your local newspaper or website. (Note: many papers only list them

one day per week. Also, we will assume that homes come up for sale randomly.) Record the

sales prices for 36 randomly selected homes recently listed in the county and indicate whether you found them in the paper or on the website. Include the reference.

Complete the table:

Describe the data

1. Compute the following: (include the session window)

x ¯ size 12{ {overline {x}} } {} = s = n =

2. Define the Random Variable X ¯ size 12{ {overline {X}} } {} in words:

3. State the estimated distribution to use. Use both words and symbols.

Find the confidence interval

1. Using Minitab, calculate the 90% confidence interval and determine the error bound. (include in the session window)

a. Confidence Interval:

b. Error Bound:

2. How much area is in both tails (combined)? α =

3. How much area is in each tail? α 2 size 12{ { {α} over {2} } } {} =

4. Using Minitab, create the graph for the 90% confidence interval created above. (Graph → Prbability Distribution Plot→View Probability) Include the graph with this lab.

5. Some students think that a 90% confidence interval contains 90% of the data. Use the list of data on the first page and count how many of the data values lie within the confidence interval. What percent is this? Is this percent close to 90%? Explain why this percent should or should not be close to 90%.

6. How many house prices would be needed in the sample to ensure that the error was no more than $2000 for the 90% confidence interval?

Describe the confidence interval

1. In two to three complete sentences, explain what a Confidence Interval means (in general), as if you were talking to someone who has not taken statistics.

2. In one to two complete sentences, explain what this Confidence Interval means for this particular study.

Use the data to construct confidence intervals

1. Using the above information, construct a confidence interval for each confidence level given. (include the session window information)

Confidence Level Error Bound Confidence Interval
85%
95%
98%
99%

2. What happens to the EBM as the confidence level increases? Does the width of the confidence interval increase or decrease? Explain why this happens.

Effect of an outlier

Suppose one of the values input incorrectly. Choose one data value and increase the amount by adding two extra zeroes. (include in the session window)

1. Calculate the 90% confidence interval: _____________

2. Calculate the Error Bound: ____________

3. How does the outlier affect the width of the confidence interval? Use complete sentences.

Part ii

Heights of 100 Women (in Inches)

59.4 63.8 61.8 61.3 61.5 62.9 64.3 60.8 57.9 64.0
71.6 62.9 60.6 59.2 64.3 63.1 65.0 65.5 58.5 66.4
69.3 63.0 69.8 64.1 62.9 62.2 64.1 62.3 63.4 61.2
65.0 63.9 60.0 59.3 60.6 58.7 61.1 65.5 69.2 60.4
62.9 68.7 64.9 64.9 63.8 64.7 65.3 64.7 65.9 58.7
66.5 65.5 66.1 62.4 58.8 66.0 64.6 58.8 62.2 66.7
61.7 61.9 66.8 63.5 64.9 60.5 59.2 66.1 60.0 67.5
55.2 69.6 60.6 60.9 65.7 64.7 61.4 64.9 58.1 63.2
67.2 58.7 65.6 63.3 62.5 65.4 62.0 66.9 62.5 56.6
66.5 63.4 63.8 66.3 70.9 60.2 63.5 57.9 62.4 67.7

1. Listed above are the heights of 100 women. These are in the student data file in the lab. Use MiniTab to randomly select 10 data values. (Calc → Random data → data from a column)

2. Calculate the sample mean and sample standard deviation and record our answer below. Assuming that the population standard deviation is known to be 3.3. Construct a 90% confidence interval for your sample of 10 values. Write the confidence interval you obtained below.

3. Repeat #1 and #2 nine more times, and record the 90% confidence interval for each of your samples. (Note: since you are randomly selecting the 10 data values you may use the same one in more than one sample. Include this portion of your session window)

  • x ¯ size 12{ {overline {x}} } {} = s = CI =
  • x ¯ size 12{ {overline {x}} } {} = s = CI =
  • x ¯ size 12{ {overline {x}} } {} = s = CI =
  • x ¯ size 12{ {overline {x}} } {} = s = CI =
  • x ¯ size 12{ {overline {x}} } {} = s = CI =
  • x ¯ size 12{ {overline {x}} } {} = s = CI =
  • x ¯ size 12{ {overline {x}} } {} = s = CI =
  • x ¯ size 12{ {overline {x}} } {} = s = CI =
  • x ¯ size 12{ {overline {x}} } {} = s = CI =
  • x ¯ size 12{ {overline {x}} } {} = s = CI =

Discussion questions

1. The actual population mean for the 100 heights given above is μ = 63.3. Using the samples above, for how many intervals does the value of μ lie between the endpoints of the confidence interval? .

2. What percentage of the total number of confidence intervals generated contain the mean μ?

3. Is the percent of confidence intervals that contain the population mean μ close to 90%?

4. Suppose we had generated 100 confidence intervals. What do you think would happen to the percent of confidence intervals that contained the population mean? Use 2 – 3 complete sentences.

5. When we construct a 90% confidence interval, we say that we are 90% confident that the true population mean lies within the confidence interval. Using complete sentences, explain what we mean by this phrase in terms a non-statistician would understand.

6. Some students think that a 90% confidence interval contains 90% of the data. Use the first confidence interval calculated and count how many of the 100 data values lie within that confidence interval? What percent is this? Is this percent close to 90%? Using 3 – 4 sentences to explain why it should or should not be close to 90%.

Questions & Answers

I'm interested in biological psychology and cognitive psychology
Tanya Reply
what does preconceived mean
sammie Reply
physiological Psychology
Nwosu Reply
How can I develope my cognitive domain
Amanyire Reply
why is communication effective
Dakolo Reply
Communication is effective because it allows individuals to share ideas, thoughts, and information with others.
effective communication can lead to improved outcomes in various settings, including personal relationships, business environments, and educational settings. By communicating effectively, individuals can negotiate effectively, solve problems collaboratively, and work towards common goals.
it starts up serve and return practice/assessments.it helps find voice talking therapy also assessments through relaxed conversation.
miss
Every time someone flushes a toilet in the apartment building, the person begins to jumb back automatically after hearing the flush, before the water temperature changes. Identify the types of learning, if it is classical conditioning identify the NS, UCS, CS and CR. If it is operant conditioning, identify the type of consequence positive reinforcement, negative reinforcement or punishment
Wekolamo Reply
please i need answer
Wekolamo
because it helps many people around the world to understand how to interact with other people and understand them well, for example at work (job).
Manix Reply
Agreed 👍 There are many parts of our brains and behaviors, we really need to get to know. Blessings for everyone and happy Sunday!
ARC
A child is a member of community not society elucidate ?
JESSY Reply
Isn't practices worldwide, be it psychology, be it science. isn't much just a false belief of control over something the mind cannot truly comprehend?
Simon Reply
compare and contrast skinner's perspective on personality development on freud
namakula Reply
Skinner skipped the whole unconscious phenomenon and rather emphasized on classical conditioning
war
explain how nature and nurture affect the development and later the productivity of an individual.
Amesalu Reply
nature is an hereditary factor while nurture is an environmental factor which constitute an individual personality. so if an individual's parent has a deviant behavior and was also brought up in an deviant environment, observation of the behavior and the inborn trait we make the individual deviant.
Samuel
I am taking this course because I am hoping that I could somehow learn more about my chosen field of interest and due to the fact that being a PsyD really ignites my passion as an individual the more I hope to learn about developing and literally explore the complexity of my critical thinking skills
Zyryn Reply
good👍
Jonathan
and having a good philosophy of the world is like a sandwich and a peanut butter 👍
Jonathan
generally amnesi how long yrs memory loss
Kelu Reply
interpersonal relationships
Abdulfatai Reply
What would be the best educational aid(s) for gifted kids/savants?
Heidi Reply
treat them normal, if they want help then give them. that will make everyone happy
Saurabh
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Collaborative statistics (with edits: teegarden). OpenStax CNX. Jul 20, 2009 Download for free at http://legacy.cnx.org/content/col10561/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Collaborative statistics (with edits: teegarden)' conversation and receive update notifications?

Ask