The key is the use of statistically derived random sampling procedures. These ensure that survey results can be defended as statistically representative of the population. Surveys that do not follow these procedures can produce results that lead to misguided market research, strategic, or policy decisions. Any so-called "survey" in which no attempt is made to randomly select respondents, such as call-in readers' or viewers' "polls", is likely to produce results that in no way reflect overall public opinion--even if many thousands of individuals participate. It is true that sampling randomly will eliminate systematic bias The mathematical theorems which justify most frequentist statistical procedures apply only to random samples. http://www.ma.utexas.edu/users/mks/statmistakes/RandomSampleImportance.html no author,

COMMON MISTEAKS MISTAKES IN USING STATISTICS: Spotting and Avoiding Them 4/10/12
Moore and McCabe (2006), Introduction to the Practice of Statistics, Third edition, p 219 Sample Distribution and Sampling Error
Distributions of populations of scores have been discussed. However, a single score does not accurately represent the population. A sample, or subset, of the population is a better estimator of the population. Alternatively, a sample that has received some treatment can be compared to the original population. Just as there is a distribution of scores for a population, there is a distribution of samples (or sampling distribution) for a population. These distributions become perfectly normal when all scores, or all samples, are included. All possible scores/samples are rarely available or possible, but the population can be reasonably represented by proper sampling.******** If the samples are randomly chosen, they are likely to be more representative of the population than a single score is. In addition, the larger the random sample is, the better the representation will be. The sample will likely be different than the population, but the...

...Business Statistics
Chapter 7
Sampling and Sampling Distributions
6-1
Learning Objectives
In this chapter, you learn:
The concept of the sampling distribution
To compute probabilities related to the sample
mean and the sample proportion
The importance of the Central Limit Theorem
To distinguish between different survey
sampling methods
To evaluate survey worthiness and survey errors
7-2
Reasons for Drawing a Sample
...

...SAMPLINGSAMPLING
SAMPLING DISTRIBUTION
(THEORETICAL)
SAMPLING TECHNIQUES (APPLIED)
8/13/2014
QM_Session 14 15
SAMPLING TERMS
An unit/element is the entity on which data are collected.
A population is a collection of all the units/elements of
interest.
A sample is a subset of the population.
The sampled population is the population from
which the sample is drawn.
A frame is a list of the elements/units that the...

...Population and Sampling
MTH/231
August 29, 2012
Importance of Population and Sampling
History from Political Arithmetic to Statistics
The history timeline show evidence of statistical data as early as Ancient Greece time but records show statistics in late 16th century, when it was introduced by, John Graunt, William Petty, and Pascal and later in 17th century by Gottfried Achenwall. It was an exciting time when success and discoveries raised the...

...Application of sampling distribution
Joe Greene, a new manager at Pilgrim Bank wants to better understand profitability data for bank’s customers. Joe is able to obtain a random sample of 31,634 customers on the following variables – Profitability (in $, for the most recent completed year, i.e. 2006), whether or not the customer uses the online banking channel, customer tenure, age and income where available, as well as the customer’s residential area....

...Population and Sampling
MTH/231
Fahad M. Gohar
Statistical data dates back to as early as Ancient Greek time, where it was introduced by John Graunt, William Petty and Pascal in the 16th century. It was then re-introduced by Gottfriend Achenwall in the 17th century. This was a very exciting time for scientists, astronomers and physicists alike as it raised the confidence and knowing that the laws of nature were not of divine intervention. As the years...

...SAMPLING DISTRIBUTIONS
|6.1 POPULATION AND SAMPLING DISTRIBUTION |
|6.1.1 Population Distribution |
Suppose there are only five students in an advanced statistics class and the midterm scores of these five students are:
70 78...

...
Sampling and Data Collection Plan
Name
QNT/561
October 27, 2014
Instructor
Introduction
Royal Blue Airlines is a medium sized airline company offering flights throughout the United States, Mexico, Caribbean Islands, and Latin America. The company operates a fleet of Boeing 737 aircrafts and is in the process of replacing older ones with newer, state-of-the-art planes. These new planes are very expensive, so management wants to maximize passenger count. A...