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Sampling

99% and 95% Confident Population Estimates

The real estate assessor for a county government wants to study various characteristics of single-family houses in the country. A random sample of 70 houses reveals the following: - Heated area of the house (in square feet): X =1,759, S=380. - 42 houses have central air-conditioning. a. Construct a 99% confidence interv

Sample Size for Population Mean Estimation

An advertising agency that serves a major radio station wants to estimate the mean amount of time that the station's audience spends listening to the radio daily. From past studies, the standard deviation is estimated as 45 minutes. a. What sample size is needed if the agency wants to be 90% confident of being correct to wit

Means of the Sampling Distributions

1. What symbol is used to represent the mean of the sampling distribution of y-(ybar)? Explain 2. What symbol is used to represent one value from the sampling distribution of y-(ybar)? Explain

Calculating Customers Needed for a Good Sample

What information would you need to know to decide how many customers should be included in the sample? If you wanted to infer the population mean level of satisfaction within plus or minus 0.5 points at a .05 level of significance, how many customers should be included in the sample? Explain how you calculated your answer.

Statistics Study Questions

1) Identify the level of measurement for data that can be classified according to color. a. Ordinal b. Interval c. Nominal d. Ratio 2) Identify the level of measurement for data that are the rankings of a movie ranging from poor to good to excellent. a. Nominal b. Ordinal c. Interval d. Ratio 3) What method of data

The following sample observations were randomly selected

Please help answer the following statistics problems. DQ1: The following sample observations were randomly selected. X: 4, 5, 3, 6, 10 Y: 4, 6, 5, 7, 7 Determine the coefficient of correlation and the coefficient of determination. Interpret. DQ2: The following sample observations were randomly s

Estimation of Sample Sizes: Provide an overview of the contents and apply the concepts to the Job Satisfaction survey.

Provide an overview of the contents of the attached article and apply the concepts to a Job Satisfaction survey. It is important to cover the concept of the techniques used to estimate sample size. The article is "Simple rules shape proper sample size." Found in Marketing News, page 38 on February 1, 2004, copyright by the Am

Overview of Statistics: Sampling & Job Satisfaction

Provide an overview of the contents of this article and apply the concepts to the Job Satisfaction survey (Job Satisfaction Survey is listed below article). It is important to cover the concept of the techniques used to estimate sample size. Sampling Size: What the Books Don't Tell You Trying to develop the perfect sampling

Sampling distributions and random variables.

It's 10 PM - do you know where your trash can is? In our neighborhood, there have been a varying number of black bear visits each year over the past six years. These visits usually result in a lot of late night noise and mess to clean up in the morning, as the black bears tip over the trash cans and dine on the contents. The

Classification of Data

1 Classify each as nominal-level, ordinal level, interval-level, or ratio-level data. a.time needed for racing cars to make a practice drive _____________________ b. horsepower of automobile engines ___________________________________ c. salaries of cashiers at Acme supermarkets _____________________________ d. r

Sampling over census

Explain why sampling is essential to many research designs, and why, if done correctly may be more accurate than attempting census measurement.

Change of Variable Technique

Given f(x) = 2x, 0 < x < 1, and a random sample of size two, X1, X2. Show that (see attached) = 7/8 using change of variable techniques. (See attached file for full problem description with proper equations)

Estimate the sample size.

You are studying the effect of two different methods of relaxation therapy. These two have never been compared before. The population mean for method 1 is 100 on a standardized score of relaxation. The population mean for method 2 is 102 on the same standardized test. The population standard deviation for both methods is 5.

Satisfactory sample

A biologist has mixed a spray designed to kill 70 percent of a certain type of insect. If a spraying of 200 such insects killed 130 of them, would you conclude that this mixture was satisfactory?

Employee morale and productivity

Your company has experienced problems with employee morale and productivity. The consultant that was hired submits a report that includes opinions and data collected from 300 secretaries and clerks as well as 75 senior managers. You are in charge of putting the provided recommendations in perspective and comment on the quality o

Dispersion and distribution

I need assistance determining Standard deviation, distribution, mean, mode, and population dispersion. --- In this Unit, you studied several measures of central tendency. By far the most frequently utilized of these measures is the mean of a population. Remember that the source of the data that you want to analyze always co

Sampling Design alternative

Explain a sampling design that is an alternative to random sampling and provide an example.

Population of a Subway Car Statistics Problem

2. The ages of a group of people in a subway car are: 5, 7, 12, 21, 29, 30, 33, 46, 52, and 83. Consider this to be your population. Find µ. Then place each number (age) on a strip of paper, fold them twice, and place them in a hat or bowl. Randomly select 3 separate samples of 5 ages each (be sure to replace the chosen

Sample Size..

You are to conduct a sample survey to determine the mean family income in a rural area of central Florida. The question is, how many families should be sampled? In a pilot sample of 10 families, the standard deviation of the sample was \$500. The sponsor of the survey wants you to use the 95 percent confidence level. The estim

Sampling Exercises

The commuter train running between Orange County and downtown L.A. has an average speed of 60 mph with a standard deviation of 4.4 mph. As a consultant to the Dept. of Transportation in California, you examined 40 trains and recorded their average speeds. 1) What are the theoretical parameters for the sampling distribution b

Sampling and Subjective probability

1) Why do you use sampling? Can you provide an example? 2) How many different types of sampling are there. 3) Why do we want to assume that our sample data represents a population distribution? 4) What are some conditions under which business decisions are made using subjective probability concepts? Could you please c

Sample mean larger than specified population

Recent studies indicate that the typical 50-year-old woman spends \$350 per year for personal-care products. The distribution of the amounts spent is positively skewed. We select a random sample of 40 women. The mean amount spent for those sampled is \$335, and the standard deviation of the sample is \$45. What is the likelihood of

Test for Single Samples

1. A cognitive psycholgist believes that a particular drug improves short-term memory. The drug is safe, with no side effects. An experiment is conducted in which 8 ramdomly selected subjects are given the drug and then given a short time to memorize a list of ten words. The subjects are then tested for retention 15 minutes

Sample of Values from Uniform Distribution

1) You want to collect a sample of values from a uniform distribution where ? is unknown but ? = 10. (a) How large a sample would you need to estimate the value of ? within 2 units with a confidence of 95%? (b) How large a sample would you need to estimate the value of ? within 2 units with a confidence of 99%? (c) If the

Multi-Parameter Likelihood Ratio Tests

6.5.3(b) Lex X1,...Xn and Y1,..Ym are independent random samples from N( θ1, θ3) and N( θ2, θ4), respectively. Show that the likelihood ratio test for testing H0: θ3= θ4, θ1 and θ2 unspecified, against H1: θ3 ^= θ4, θ1 and θ2 unspecified, can be based on the random variable F= Sum from 1 to n (Xi-Xbar)^2/

Type of study

In conducting his study of reactions to unemployment, Peter tries to select every 10th unemployed person in his country for a telephone interview. Peter had trouble identifying the entire population (no central lists were kept) and could not contact all the potential participants he could identify, because some of them did not

Major problem of sample

Dr. Bundy recently earned permission from the warden of a local prison to use prisoners to study the effects of the drug Zoloft on depression. He wants to be able to generalize the results obtained from the study to the general population of adults in the United States. Where is the major problem with using this sample?

Sampling method for a telephone survery

I am choosing participants to call for a telephone survery of campus drinking patterns. If I get a list of all the students on campus, and select every 10th student to call have I chosen a. Population b. Simple random sampling c. Systematic random sample d. Representative sample I feel that this is c. Am I in the ball

Survey Drinking Patterns

Yolanda is choosing participants to call for her telephone survey of campus drinking patterns. She gets a list of all students on campus and selects every tenth student to call. She has chosen a: a. Population b. Simple random sample c. Systematic random sample d. Representative sample.

Simple and Stratified Random Sampling

Edward is conducting a survey of attitudes about the Head Start program. He wants to make sure he has members of all important subgroups of the American population in his sample. What sampling technique should he use? a. Simple random sampling b. Stratified random sampling c. Quota sampling d. Snowball samplin