PQ Systems - Quality eLine
>> In this issue:
 

Concurrent licensing gives users more options

Quality Quiz: With a video!

Data in everyday life

Six Sigma and more

Bytes and pieces

FYI: Current releases

 
>> Be social:
 

Visit our Quality Blog and Twitterfollow us on Twitter.

 
>> Sign up:
 

Just type in your friend's e-mail below to have them receive Quality eLine:

 
>> Software:
 

CHARTrunner

GAGEpack

SQCpack

CHARTrunner-m

DOEpack

Quality Gamebox

 
 

Quality Quiz:Professor Cleary
Another quiz from Professor Cleary

Congratulations: "B" is correct!

When in doubt, make something up—or at least that seems to be Quinn’s operating principle here, since there is no such thing as a “systematic cluster sample.” He has confused “systematic sample” and “cluster sample,” which are two very different things.

In a systematic sample, the first sample is selected randomly, and subsequent samples follow at evenly spaced intervals until the desired sample size is reached.

Systematic sampling is especially useful with a large population. For example, I once needed to estimate average age for staff members at my university. Records were in a number of separate files in the Human Resources office, numbered from 1 to 1,500. Since I needed a sample size of 150, I went to a table of random digits to select a number from 1 to 10 (it happened to be 7). Then I started the sample with number 7, followed by 17, 27, 37, etc., until I reached 150 samples.

Subtle differences distinguish systematic sampling from cluster sampling:
A cluster sample, on the other hand, separates a population into separate groups called clusters. This approach works best when each cluster represents the characteristics of the entire population. Then samples are selected randomly from each cluster group.

>> Watch a more complete video explanation

Quality Quiz Classics

Click here to register to win a free copy of
Quality Quiz Classics

 
PQ Systems  |  Proof of quality.


PQ Systems, Inc.  |  210 B East Spring Valley Road, Dayton, OH 45458  |  800-777-3020

Copyright 2010 PQ Systems, Inc. All rights reserved.