Minimum sample size

Could you please direct me to the “source”?  Thanks!
Kindly,
Bruno

Hello Louise,
I have a three page document about how to calculate sample sizes for both Variable Data analysis and Discrete Data analysis.   It is part of our black belt training manual. 
If you provide me with your email address, I will send it to you.
Helper

It Depends:
Based on some knowledge of call centers you have a large stratification of calls. You did not state your intended goal so I would 1) Stratify the nature ofthe incoming calls, 2)Take your sample from a proportionate representative sample.
i.e. if you have 10% Technical, 80% informational, 10% Financial use these to select the number of each type to obtain information.
 
Regarding the number of samples: use the maximum number you can analyze in the time you have to performr this task. More is better.
If you are looking for a minimum number use a simple software package avaialbe to calculate power and size.
 

Hi Helper thanks for the offer that sounds very useful, my email is [email protected]

Hi Helper,
Can you please share that we me too? I had posted an article some time back on the same ( in response to another post- I had checked with somebody else, and had come up with 3 different formulas..each of which was right in its own way..but gave different results)
, so i would appreciate a standard formula.
My email is [email protected]
Thanks in adv,
George

Dear Louise,
 
The sample size that you want to decide will depend on how minutely do you want to  onitor the calls received, in other words what is the margin of error that you are OK to live with, it statistical terms what is the confidence level and confinence interval that you are looking for in your test.
 
In the given scenario, the thumb rule is to go with 95% confidence level and 98% confidence interval. So you receive 25000*7 calls per week.  So you can monitor 2,369 calls per week.  If working days are 5 then you may monitor 2356 calls per week.
 
After a given population size, sample size becomes independent.  Therefore you may have seen bevy little decrease in sample size even though thepopulation has reduced majorly.
 
You may easlity find on the net online sample size calculators.  Read some more articles and also learn about the power of test.
 
Let me know if I can be of any further help.
 
Amit

I tried the link for mentorsoft and it did not work, the link to http://www.dbar-innovations.com did work. When I got there I discovered it was a software system with a DMAIC Mentoring style analysis system and a tracking program. No info on consulting, but interesting system.

Use a sample size calculator..