MiC Quality MiC Quality QUARTERLY UPDATE
APRIL 2011 
  Click here for the Web version of the current issue  
Online Course Instructor
Glen Netherwood
MiC Quality

 

Past Issues

January 2011

October 2010
July 2010
April 2010
January 2010
July 2009
April 2009

December 2008

October 2008
June 2008
April 2008
February 2008
December 2007
October 2007
August 2007
June 2007
April 2007
February 2007
 
 
 

 

 

In Focus: SAMPLING METHODS

In this issue:

To unsubscribe please use the contact form and select "Unsubscribe from Updates".

:: Specials

We are offering Double Access Time - 8 weeks instead of the usual 4 weeks if you enroll before midnight of May 10, 2011

:: Special: 8 WEEKS

For ALL Enrollments
QUOTE Promotional Code D2X
ENROLL NOW

This Special expires at midnight May 10, 2011
 
:: Sampling Methods

The purpose of sampling is to determine the characteristics of a population using a relatively small sample taken from the population.

If a sample is to give meaningful results it must be representative of the population. There are various ways of attempting to achieve this.

Convenience Sampling is a sampling method in which units are selected based on easy access/availability. The disadvantage of convenience sampling is that the units that are easiest to obtain may not be representative of the population:

  • products on top of a box of parts may be a different quality from those at the bottom
  • people who are at home when the market researcher calls may not be representative of the entire population

Random Sampling involves taking items for the sample in a way that ensures that any unit in the population has an equal chance of being selected. This is intended to ensure that the sample is not biased by the method of collection. Bias may be inadvertently introduced by selecting items that are easy to collect, or accessible.

Stratified Sampling is a sampling method in which the population is split into several categories that share common characteristics. Items are collected at random from each category, in proportion to the size of the category relative to the population. Stratified sampling may give more reliable results than pure random sampling because it ensures that all categories are fairly represented.

Systematic Sampling involves taking a sample from the available data in a set pattern, rather than at random. A telephone survey that called every hundredth caller listed in the phone book would be a systematic sample. Systematic sampling is often convenient and economical, but carries the risk that there will be an unsuspected systematic pattern in the data.

For more information on sampling refer to MiC Quality Six Sigma Glossary.

MIC QUALITY ONLINE COURSES
:: Six Sigma Primer
:: Statistical Process Control (SPC), Advanced Statistical Process Control
:: Design of Experiments (DOE), Advanced Design Of Experiments
:: Primer in Statistics, Advanced Statistics
:: Measurement Systems Analysis (MSA)/ Gage R&R
:: FREE Excel Primer
:: FREE Sample Module "Introduction to Statistics"
:: ALL COURSES
FREE Statistics Reference Booklet
FREE Six Sigma Summary Booklet
DOWNLOAD Brochure for All Courses


FREE SIX SIGMA TRAINING RESOURCES
:: 

500+ terms Six Sigma Glossary
(includes all terms in the ASQ SSBB Six Sigma Black Belt Body of Knowledge)

::

Sigma Calculator

::

Book Reviews

:: Reference Tables
:: Next Update

The next update will be in July 2011.

[Top]
NEW

 

 

MiC Quality