posted 08 November 2000 06:39 PM            

I work in a customer service center and we are attempting to decide on the right sampling plan for our Quality Assurance program. I am not quite sure which one is appropriate or how to justify the method once chosen.

Basically, we have several different touchpoints (web based chat, email, phone) and low volume but many clients. We want to give a 95% confidence level, with 4% margin of error on both the client (external) and rep (internal) levels.

Any advice and/or directions to resources would be much appreciated.

posted 16 November 2000 12:25 PM               

The formula for finding the sample size (assuming a continuous process that is in control) is:

n = sample size.
p = estimate of process percent defective.
Zcl= Z score of confidence level (remember
that this is a two sided estimate so
you have to use half the confidence
factor on each side, for 95% confidence
level you use 97.5% to find the Z
score).
E = Allowable error of the process percent
defective.

2
Zcl x p x (1-p)
n = ---------------
2
E

In essence, the sample size is equal to the Z score squared times the percent defective time 1 minus the percent defective divided by the allowable error squared.

References:

Process Quality Control by Ellis Ott, ISBN 0-07-047923-2, pages 76 - 79.

Modern Methods for Quality Control and improvement by Wadsworth, Stephens, and Godfrey, ISBN 0-471-87695-X, pages 173 - 176.

posted 16 November 2000 01:56 PM            

What other methods would you suggest we use?

posted 16 November 2000 05:10 PM               

Quality Control by Dale Besterfield, ISBN 0-13-745232-2

posted 16 November 2000 05:21 PM            

I have done some research into statistics and I admit that some of it goes way over my head.

I agree that as population decreases, the company will have to sample a LOT more to get the sort of accuracy we want.

Because our population is fairly low, I decided to use a longer time frame. As I stretch it out over a month and longer, the sessions to be reviewed decreases to a point where it is feasible to QC. Of course, we can't QC at the end of the time frame so we're using historical data to forecast and break up the QC on a daily basis.

That's been my solution so far, what do you think?

posted 23 November 2000 10:16 PM               

I am woking with several operating companies within my organization in their quality journey modelled after Baldrige Criteria. One of the area we focused on is "Customer Service" which deal with access mechanism (similar to your touchpoint). However, so far, we have not used any staistical method to determine the most preferred access mechanism but the following methods :-

1) Customer survey, though time consuming and subjected to realibility. This is to determine customer most preferred access mechanism (normally designed into the questionaire). Then do a Pareto chart
2) Data collection when customer call in and do a Pareto chart for most frequently used access mechanism
3) "do what others do" i.e. follow the market trend or competitor

However, the decision to provide which access mechanism depends on company's strategy and affortability. There is not standard way but to meet customers needs.

I could share more of my experience when I get a better understanding of your objective.

Hope this help

------------------
Thanks and Best Regards

lmfoong

posted 30 November 2000 02:20 PM               

In our company we handle about 650 tele calls a day, receive 1,000 faxes, 400 on-line orders.
We have all the technology as mentioned above to gather data on an hourly basis so we are at an advatage here...
We used customer surveying to find out what our customers wanted in service and we used QFD to structure the department(s), and determine our "touchpoints".
Here's some data to think about, because I think that your customers may be somewhat the same ours;
1. Customers want to make contact easy, fast, and user-friendly.
2. they want prompt, timely & responsive service.
3.They want their request to be handled once and only once.
4. Service must be error free.

We measure the call center on # in-coming/out-going calls, # adandoned calls, # Overflow calls, average time per call, # input errors, # abandoned webpage hits, etc, etc. This is done daily but also the data is used for strategic planning therefore is charted by month, quarter and annual.
We have found that we have violated customer requirement when:
a. There are more than 5 abandoned calls,
b. There are more than 1 Overflow calls (these are calls that are bounced out of the que to receptionist)
c. A call takes longer than 2min 50 seconds.
d. There is a mistake on 10 orders out of 1,600 per day.
e. We don't communicate back to them about ambiguous information from our webpage within 2 hours of receipt of request and within 3 hours of receipt of fax request.

What I'm suggesting is that in your original message you had a margin of error of 4%, which you may find is quite liberal! Did you mean .004%. We have found by listening to customers that the margin of error in most industries today is almost zero, due to technology, competition, and the demographics of society....

hope this helps.

P.s.Rick Goodson...great response for sample plan!!! This approach is quit necessary in a controlled customer service environment. But control in a dynamic department like C/S and Sales takes time, determination and guts...it's one of the hardest things to control and measure. Only now are we reading about pioneers in the area of quality and sales i.e Paul Seldon, Cas Welch.