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Sampling

Sampling is utilized in statistics to survey a specific subset of a population as it is often not feasible to collect observations for an entire population. Sampling allows various descriptive statistical measures to be computed and these statistics are then useful in trying to estimate or infer the parameters for the entire population.

When conducting a statistical analysis, sampling basically simplifies the process. If a population contained 1 billion subjects, a researcher would be delusional to assume that all 1 billion individuals could be observed or surveyed. However, with sampling, a smaller portion of the individuals from that population could be analyzed. Then, through the use of inferential statistics, estimations could be made with regards to specific parameters applying to the entire population.

There are a multitude of different sampling techniques which can be employed when analyzing a population. Specifically, the most common sampling methods practiced are cluster sampling, systemic sampling, random sampling, nonprobability sampling, and stratified sampling. All of these sampling practices differ in terms of the criteria they use to collect samples and in certain situations one technique may be preferred over another.

In many cases, sampling needs to be implemented because it is impossible or too difficult to identify every unit in a population. Consider particular animal populations, such as sharks. It is not possible to count every shark residing in an ocean. Therefore, through sampling, statistical analyses can be done on populations of specific shark species and reasonable estimations can be construed regarding their total population size.

Clearly sampling is an integral part of any statistical study. However, sampling requires both resources and time, which are finite properties. Therefore, understanding the array of different sampling methods which are possible and when it is best to perform them is critical to efficient sampling in statistics.

Categories within Sampling

Cluster Sampling

Postings: 0

Cluster sampling is a specific type of sampling technique which is used on homogeneous populations and these target populations are divided into groups which are randomly sampled.

Systematic Sampling

Postings: 2

Systematic sampling is a form of random sampling in which units are selected in an ordered fashion according to a periodic interval, i.e. the 3rd or 5th person on every list is sampled.

Random Sampling

Postings: 30

Random sampling is when every single element in an entire population has an equal probability of being selected.

Nonprobability Sampling

Postings: 2

Nonprobability sampling is not based on the probability theory because elements are not randomly selected and it is a technique often used for qualitative research.

Stratified Sampling

Postings: 1

Stratified sampling is a method in which a population is divided into separate groups, called strata, based upon specific characteristics such as gender or age.

Exploratory Analysis of Quantifiable Variables

Using information from Page 5- 15: What are the four purposes of this chapter: (1) describe the research methodology of this study, (2) explain the sample selection, (3) describe the procedure used in designing the instrument and collecting the data, and (4) provide an explanation of the statistical procedures used to analyze t

Clustered and stratified sampling

A. Design effects are used to evaluate the precision of statistics for different sample design. Is the design effect of a clustered element sample likely to be larger or smaller than one? Is the design effect of a stratified element sample likely to be larger or smaller than one? In a single stage clustered sample, if within

Collecting Data from a Telephone Survey

A person decides to take a telephone survey of 40 families in the 721-exchange area (sometimes referred to as prefix). You want an excellent representation of all subscribers in the exchange area. Explain how you will carry out this study.

Statistical Data Measures

Classify each of the following as nominal, ordinal, interval or ratio data: a) The time required to produce each tire on an assembly line. b) The number of quarts of milk a family drinks in a month. c) The ranking of four machines in your plant after they have been designated as excellent, good, satisfactory, and poor. d)

Western Electric runs rule

See attached for data. 1. A Lean Six Sigma black belt project results in a lower defective rate at the final inspection of a plastic molded component. Thirty days of data presented in the following table. (a) Create the appropriate control chart for the improved process. Apply only Western Electric runs rule 1 for deter

Machine Learning Question

I have been giving the following problem in machine learning which I am new to. Is there a specific concept that this problem is testing; so maybe I can do some reading/research on it and try applying those principles to the problem? Thanks for any help/hints/direction. You are a visiting Professor in the first and only Unive

Choosing the Right Sampling Designs

I'm practicing on choosing the right sampling designs. I have come up with answers below but I do not think they are correct. Please, verify and provide the correct answer with explanations. What kinds of sampling designs would be used for the following? a. A study to get a quick idea of the medical acceptability of a ne

Statistics Problem Set: Independent and Dependent Variables

1. The Chicago Tribune of July 21, 1995 reported on a study by a fourth-grade student named Beth Peres. In the process of collecting evidence in support of her campaign for a higher allowance, she polled her classmates on what they received as an allowance. She was surprised to discover that the 11 girls who responded reported a

Mean of Sampling Distribution

The assets (in billions of dollars) of the four wealthiest people in a particular country are 47,35,28,11. Assume that the sample of size 2 are randomly selected with replacement from this population of four values. a) After listing the possible samples and finding the mean of each sample, use the table to describe the sampli

Flexible Working Schedule for Women with Children

Companies often make flextime scheduling available to help recruit and keep women employees who have children at home. Other workers sometimes view these flextime schedules as unfair. An article in Nikkei Article indicated that 5% of male employees state that they have to pick up the slack for moms working flextime schedules. Su

Selecting Appropriate Survey Techniques

The human resources (HR) manager for Gargantua, Incorporated wants to give a short survey to a sample of recent hires (defined as people who have been with the company for less than one year). This sample will include several thousand individuals. The HR manager wants to be able to develop a confidence interval for the proportio

What sample size is necessary for a study

Problem is: What sample size is ncessary for a study to determine the average cost of a child delivered at a local hopsital within the past 3 months? (I have determined a sample size of 1,300. I came up with this number because there are 10,416 births a year in Louisville, KY where the basis of this problem is. 10,416 / 12 m

Statistics Problems

The branch manager of a pet supply store wants to study characteristics of customers of his store. In particular, he decides to focus on two variables: the amount of money spent by customers and whether the customers own only one cat. 1. If he wants to have 95% confidence of estimating the true population mean amount spent in

Sampling Distribution of a Sample Mean: University Tuition

According to the College Board's report, the average tuition and fees at four year private colleges and universities in the United States was $18,273 for the academic year 2002 - 2003 and the standard deviation was $2100. For a random sample of 100 four year private U.S. colleges, answer the following: a. What is the mean of

Simple confidence interval and approximations

Suppose that in a population of 10 items, 3 are defective and 7 are not. Suppose that two items are chosen at random for inspection. Let X be the number of defective items inspected. report all probabilities to a minimum of 5 decimal places of accuracy. (a) Clearly explain why X does not have a binomial distribution. [Hint: W

I am not sure where to begin with the part b?

Credit card companies frequently use statistics to monitor their customerââ?¬â?¢s accounts for fraudulent activities. If any ââ?¬Å"unusualââ?¬Â? activity is noticed, the customer is contacted to make sure that the credit card has not been compromised. Listed below are the daily charges on a specific customerââ?¬

Sampling Distribution of Sample Mean Problems

I need help solving the following problem, please: The fill amount of bottles of a soft drink is normally distributed, with a mean of 2.0 liters and a standard deviation of 0.05 liter. If you select a random sample of 25 bottles, what is the brobability that the sample mean will be a. between 1.99 and 2.0 liters? b. belo

Sample Size Required - Food Poisoning

Please help with the following problem. Recently, a case of food poisoning was traced to a particular restaurant chain. The source was identified and corrective actions were taken to make sure that the food poisoning would not reoccur. Despite the response from the restaurant chain, many consumers refused to visit the restau

Systematic Sampling: Advantages and Disadvantages

Identify a sample design to use for collecting data on rancidity problems with a shipment rice bran. Using nutracea as case study www.nutracea.com. Please include the advantages and disadvantages to systematic sampling. (Ex: http://www.whfoods.com/genpage.php?tname=foodspice&dbid=128).

Sample for Height, Hourly Wage and Poll

1. People in a large population average 60 inches tall. You will take a random sample and will be given a dollar for each person in your sample who is over 65 inches tall. For example if you sample 100 people and 20 turn out to be over 65 inches tall, you will get $20. Which is better: a sample of size 100 or a sample of siz

Statistics of Doctor Appointment with a New Patient

See attached file for proper formatting. 4. The amount of time a doctor spends in an appointment with a new patient has a mean minutes and standard deviation minutes. The distribution of times is not normal. (a) Suppose a sample of 5 new patient appointments is selected. What can you say about the sampling dis

Three Worked Through Solutions for Statistics Problems

Please see attached file. Suppose you have drawn a sample of size 200 from a college and, for each student, recorded the gender of the student, and how interested the student was in watching sports on television on a 1-7 scale (1: not interested at all, 7: very interested). The results are summarized as the following cross-ta

Statistics Probability for Sample Means

1. Suppose you have drawn a simple random sample of 10 students from a college campus and recorded how many hours each student surfed the internet during the first week of February, 2010. Results: Student: 1 2 3 4 5 6 7 8 9 10 Hours of Internet Surfing: 9 12 4 10 5 18 8 12 6 6 For this sample, c

Survey Sampling for hours spent exercising daily in a certain community

Suppose that a survey is being planned for purposes of estimating the average number of hours spent exercising daily by adults (18 years of age or older) living in a certain community. A list of all individuals living in the town is not available; however, a list of all households is available at the office of the town clerk. Fo

Ethics of Sales People

ETHICS OF SALESPEOPLE Within marketing, the area of personal sales has long suffered from a poor ethical image, particularly in the eyes of college students. An article investigated whether such options by college students are a function of the tupe of sales job (high tech versus low tech) and/or the sales task (new account

Longmont Computer Leasing Company: Mean number of pages printed in a month

The Longmont Computer Leasing Company leases computers and peripherals like laser printers. The printers have a counter that keeps track of the number of pages printed. The company wishes to estimate the mean number of pages that will be printed in a month on its leased printers. The plan is to select a random sample of printers

Statistics: Ad for Moisturizing Lotion; Adult Use of Sunscreen

Can you assist me, in your own words, in setting up a full statistical and word explanation for the following: a. In an ad for moisturizing lotion, the following claim is made: '..it's the #1 dermatologist recommended brand.' What is misleading about the claim? b. In a recent article, the author states that 71% of adults d

Statistics

Please show all of the steps and processes used to solve each problem. 1. Suppose we are researching the attitudes of first year medical students at a local University. Using this example, describe in your own words how you would go about determining this through: a. Drawing a random sample b. Drawing a systematic sample

Selections and Evaluation: Statistics Problem

1-Jan 2-Jan 3-Jan 4-Jan 5-Jan 6-Jan 7-Jan 8-Jan 9-Jan 10-Jan 15 3 3 4 1 6 0 6 1 4 The next 5 days of phone calls received were as follows: 11 Jan (5) 12 Jan(6) 13 Jan (4) 14 Jan (3) 15 Jan (5) Welcome to module four's SLP. For this module, continue to collect data for five days. Is the larger sample