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Population sampling

Related Topics

Wize University Statistics Textbook > Collecting Data & Sampling

Good Sampling

4 Activities

Wize University Statistics Textbook > Estimating with Confidence Intervals

Confidence Interval for a Proportion

3 Activities

Wize University Statistics Textbook > Estimating with Confidence Intervals

Confidence Interval for a Mean

3 Activities

Wize University Statistics Textbook > Displaying & Summarizing Quantitative Data

Boxplots and Five-Number Summary

3 Activities

There are 600 Sephora locations in the United States. Christine randomly selected 40 stores, and then she randomly selected 100 customers from each of those stores. Less than 1% of her sample identified as heterosexual males. Based on her sample, the average spending at Sephora is $45. In addition, 340 customers in her sample revealed that they have VIB Rouge status, which the highest tier status that is reached when a customer spends $1,000 in a calendar year.

Which of the following is/are true? (Check all that applies.)

More Good Sampling Questions:
Statistical Sampling
A marketing agency is interested in learning about the opinion of the general public about a new product that has been developed. In their study, they randomly call 200 home phone numbers and ignore people that do not have a home phone. Which of the following is least likely to occur?
Statistical sampling
Which statment about bias is/are TRUE?
i) Selection bias is significantly reduced when the sample size is larger
ii) Non-response bias results from random variation in the samples and will always be present
Statistical sampling
A textbook publisher received 5 shipments of 100 seemingly identical statistics books each. He chooses 2 shipments at random and checks 15 of the books randomly within each shipment, and found that 3 of these books have errors. Which of the following statement is TRUE?
Statistical Sampling
To determine the average household income in a very small town, a survey was mailed to 200 randonly selected homeowners in this town. Which of the following is most likely to occur?
Statistical sampling
One of the questions in a researcher's sample survey is: "Given one of the main ways germs are transmitted is through person-to-person contact, how often do you use hand sanitizer?"This will likely lead to?
Statistical Sampling
Which of the following statement is true?
Statistical Sampling
When you are increasing the sample size, which of the following is true?
Statistical sampling
A study on wellbeing and stress of university students is conducted. The researcher drew a random sample of 5 departments on campus. Then he randomly sampled 100 students within each department that was selected and handed them the link to his online survey. Ultimately, only 30% of the sample responded. Amongst those who responded, 120 of them say they feel stressed.
(c) Which of the following is definitely true?
Statistical Sampling
Which of the following could reduce sampling bias?
More Confidence Interval for a Proportion Questions:
Confidence Interval
You are given an 99% confidence interval for the proportion of homeowners that still have a home phone →\rightarrow (0.35, 0.49)
1. What is an estimate for the proportion of homeowners having a home phone?
2. What is the standard error of the sample proportion of homeowners owing a home phone?
Confidence Interval for a Proportion
A random sample of 1000 people in Calgary were asked if they are satisfied with their mobile carriers: “YES or NO?” Results: 535 people said YES.
Confidence Interval for a Proportion
A random sample of 1000 people in Calgary were asked if they are satisfied with their mobile carriers: “YES or NO?” Results: 535 people said YES.
Confidence Interval for a Proportion
Based on a random sample of 200 households, 70 of them have at least one pet. Construct a 95% confidence interval for the households that has pets.
Confidence Interval for a Proportion
Parts (i) to (iv) are based on the following information:
In 2006, it was reported that only 40% of students at the university ask questions in lectures. It is believed that this percentage has changed. You randomly sampled 80 students and asked them "Have you ever asked a question in a lecture?" Twenty-four of them responded "Yes". There are 20,386 students at the university.
(iii) What is the p-value?
Confidence Interval for a Proportion
Based on a sample, the average time it takes a customer to eat a burger is 20 minutes with a standard deviation of 8 minutes. Furthermore, 27 customers in the sample ordered the vegetarian burger.
We are 95% confident that between 23.1% and 43.6% of all customers order the vegetarian burger. Construct a 95% confidence interval for the average time it takes all customers to eat a burger.
Confidence Interval for a Proportion
Which of the following is true for a 90% confidence interval for the population proportion.
Confidence intervals
Based on a sample of 800 children in Twin Pines, 82% of them are vaccinated. Interpret a 95% confidence interval [0.788, 0.852]\left[0.788,\ 0.852\right] in plain English.
Confidence Interval
You are given an 99% confidence interval for the proportion of homeowners that still have a home phone →\rightarrow (0.35, 0.49)
1. What is an estimate for the proportion of homeowners having a home phone?
2. What is the standard error of the sample proportion of homeowners owing a home phone?
More Confidence Interval for a Mean Questions:
Confidence Interval for a Mean
A 90% confidence interval for the mean number of pairs of shoes Justine purchases every few years is (5, 17).
Confidence Interval for a Mean
You wish to test if being a member of a union increases hourly wages, in dollars, for the average construction worker. A sample of 18 construction workers' earnings were recorded prior to and after forming a union.
The results are: mean difference = −4.135-4.135 standard deviation of differences = 7.197.19
Compute a 95% confidence interval for the mean difference in the hourly wages
Confidence Interval for a Mean
You wish to test Ho:μ=29   Ha:μ≠29H_o:\mu=29\ \ \ H_a:\mu\ne29
A 90% confidence interval for the population mean is (22, 28)\left(22,\ 28\right)
Which of the following is NOT true?
Confidence Interval for a Mean
We have an SRS of 100 people. If about 95% of the data is between 193 and 393, find the 95% confidence interval.
Confidence Interval for a Mean
The 95% confidence interval is [$800, $1,200]. The sample mean must be $1,000.
Confidence interval for a mean
According to a sample of 100 apartment suites in Twin Pines, the sample mean rent is $970. The population standard deviation is $540. Construct a 99% confidence interval for the true population mean rent in Twin Pines.
(a) The mayor of Twin Pines says that the mean rent is only $700. Is this plausible?
(b) Helen lives in Twin Pines and says her rent is only $700. Is this plausible?
Confidence Interval for a Mean
A large software development firm recently relocated its facilities. Top management has encouraged their professional employees to engage in local service activities. Based on a random sample of 24 professionals, the sample mean is 16.75 hours. The population standard deviation is 2.4 hours.
A 95% confidence interval for the true mean number of hours of volunteer time is closest to:
Confidence interval for a mean
Kevin is the quality assurance manager for Gossip Girl dolls that talk gibberish until the AA batteries run out. The commercial for the toy says: “Over 300 hours of non-stop yapping!” He randomly selects 36 dolls and finds that they talk non-stop for about 275 hours on average until their batteries are drained. The number of hours is normally distributed with a standard deviation of 25 hours.
A bored and angry mother sues the company for false advertisement. Gio, the Marketing Director, defends himself in court by saying that the toys' average number of hours is not significantly different from 300. Use the confidence interval calculated in Question 9 to determine the conclusion of the two-tailed hypothesis test at the 5% level of significance.
Confidence Interval for a Mean
Kevin is the quality assurance manager for Gossip Girl dolls that talk gibberish until the AA batteries run out. The commercial for the toy says: “Over 300 hours of non-stop yapping!” He randomly selects 36 dolls and finds that they talk non-stop for about 275 hours on average until their batteries are drained. The number of hours are normally distributed with a standard deviation of 25 hours.
Construct a 95% confidence interval for the hours of non-stop yapping.
Confidence interval for a mean
A 90% confidence interval for the average length of a pregnancy is 33 to 38 weeks.
The correct conclusion is
Confidence Interval for a Mean
A sample of 61 households that have dogs reveal that an average of $140 is spent on dog food per month. The standard deviation of the sample is $115 per month.
Construct a 90% confidence interval for the monthly mean amount spent on dog food.
Confidence Interval
(v) Which of the following is/are true? (Check all that applies.)
Confidence intervals
A large software development firm recently relocated its facilities. Top management has encouraged their professional employees to engage in local service activities. Based on a random sample of 24 professionals, the sample mean is 16.75 hours and the standard deviation is 2.4 hours.
A 95% confidence interval for the true mean number of hours of volunteer time is closest to:
Confidence intervals
Based on a random sample size of 20 people with full-time jobs, the average time they spend in the shower each morning is 16 minutes with a standard deviation of 5 minutes. Construct a 95% confidence interval.
Population Sampling: Confidence Interval
Bob, a second-year student at Twin Pines University, is not very good at statistics. He wishes to infer about the average starting salary of recent graduates at Twin Pines University. His sample included 12 friends, all recent graduates, and it revealed a mean of $55,000. His 90% confidence interval is [39,116, 80,884].
Bob reports: "We conclude that 90% of recent graduates at Twin Pines University earn between $39,116 and $80,884."
List everything that is wrong about his statement. (Check all that applies.)
Confidence Interval for a Mean
Which statement is true about a 95% confidence interval [188,212]?
Statistical errors
For the following statements, select true or false. Enter T for True, F for False. (Use capital letters: T, F)
1. The mean weight of five cats is 20 lbs. We take away one that at weights 28 lbs. The mean weight of the remaining cats is 18 lbs.
T
2. The 95% confidence interval is [$800, $1,200]. The sample mean must be $1,000.
T
Confidence interval with t-distribution
A sample of 61 households that have dogs reveal that an average of $140 is spent on dog food per month with a standard deviation of $115 per month.
Confidence Interval for a Mean
A t distribution is used instead of the normal z distribution when
Confidence Interval for a Mean
A 90% confidence interval for the average length of a pregnancy is 33 to 38 weeks.
The correct conclusion is
More Boxplots and Five-Number Summary Questions:
Boxplots: Five-Number Summary
The amount of water drank by 24 people, in millilitres, is recorded below:
500 502 503 504 505 512 700 702 703 800 840 854
860 872 883 900 910 903 905 907 933 940 1702 1823
Making Decisions Based on Center & Spread
A high school teacher is choosing her best student to participate in a math-olympics competition. She gathers the practice test scores from 10 of her students over the past 6 months. If this teacher wants to pick the best student in terms of scores and consistency to participate in this compeition, what data attributes is she looking for? (Select all that apply)
Boxplots: Five-number summary
We surveyed 39 students and asked them how much their one-way commute to school costs them. Here are the summarized data.
Which of the following is the boxplot that can be used to represent this data?
Boxplots: Five-number Summary
The following boxplots show the final exam grades from two classes -- class A and B
Which of the following statement(s) is/are true? (Select all that apply)
Boxplots: Five-Number Summary
Given the ordered data set 8, 20, 22, 26, 30, 36, 40, 50, x, which of the following value(s) of x will make it an outlier? (select all that apply)
Boxplots: Five-number summary
The 5 number summary statistics for the number of years a typical family owns their first home before selling it is given by:
0.5      1      3.5      10      300.5\ \ \ \ \ \ 1\ \ \ \ \ \ 3.5\ \ \ \ \ \ 10\ \ \ \ \ \ 30
A total of 120 families participated in this study.
Making Decisions Based on Center & Spread
A high school teacher is choosing her best student to participate in a math-olympics competition. She gathers the practice test scores from 10 of her students over the past 6 months. If this teacher wants to pick the best student in terms of scores and consistency to participate in this compeition, what data attributes is she looking for? (Select all that apply)
Boxplots: Five-number summary
We surveyed 39 students and asked them how much their one-way commute to school costs them. Here are the summarized data.
Which of the following is the boxplot that can be used to represent this data?
Boxplots: 5-number summary comparison
The number of complaints received daily over the last 20 days by two Telecommunications companies are summarized by the following boxplots.
Which of the following statements is TRUE?
Boxplots: Five-number summary
(iv) Which of the following is/are true? (Check all that applies.)
Boxplots: Interpretation
The 5-number summary statistics for the number of years a typical family owns their first home before selling it is given by:
0.5  1  3.5  6  300.5\ \ 1\ \ 3.5\ \ 6\ \ 30
A total of 120 families participated in this study.
Boxplots: Skewness and Symmetry
The 5 number summary statistics for the number of years a typical family owns their first home before selling it is given by:
0.5  1  3.5  6  300.5\ \ 1\ \ 3.5\ \ 6\ \ 30
A total of 120 families participated in this study.
Boxplots: Interpretation
The 5-Number summary statistics for the number of years a typical family owns their first home before selling it is given by:
0.5  1  3.5  6  300.5\ \ 1\ \ 3.5\ \ 6\ \ 30
A total of 120 families participated in this study.
Boxplots: Five-number Summary
The amount of water drank by 24 people, in millilitres, is recorded below:
500 502 503 504 505 512 700 702 703 800 840 854
860 872 883 900 910 903 905 907 933 940 1702 1823
Boxplots: Five-number summary
Draw a boxplot and create a range that helps identify outliers for the following data set 8, 20, 22, 26, 30, 36, 40, 50, x.
After drawing the boxplot, decide which of the following values of x are outliers (select all that apply)
Boxplots: Five-number Summary
The number of homicides is recorded for Toronto, London, Ottawa, and Winnipeg for each year over a 25 year period. The distributions are showed by the boxplots:
Which of the following is true?
Boxplots: 5-number Summary
Suppose there was an error and the lowest (minimum) house price in Sadlands is actually $285,000. When the correction is made, what will happen? (Check all that applies.)
Boxplots: Five-number summary
I randomly sample 8 wallets see how much cash is inside each of them. Results:
5 15 25 25 40 65 85 200
Statistical Properties: Practice
True or false? Enter "T" for true; "F" for false (without quotations).