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quizzman123 · Oct 23, 2009, 11:31 PM

Hi,

For a population of 10,000, what would be the sample size that need to be taken for a 80% confidence level?

How is this calculated - is it 80% of 10,000?

adam_89 · Oct 24, 2009, 05:55 AM

So you are needing to know 80% out of the 10,000 people that has confidence?

If that is the case then yes, it is 80% of 10,000

which means .8x10,000

Unknown008 · Oct 24, 2009, 08:52 AM

I don't know if that is as simple as that if the actual question resembles that one:

https://www.askmehelpdesk.com/math-s...al-390594.html

morgaine300 · Oct 25, 2009, 01:50 AM

No, adam_89. It has nothing to do with the number of people who have confidence. A confidence interval is a specific thing in statistics. And no it's not 80%. That's nothing to do with the sample size.

morgaine300 · Oct 25, 2009, 01:54 AM

The equation for a sample size, given a normal distribution, is:

$n\ =\ \left(\frac{z\sigma}{E}\right)^2$

Or

$n\ =\ \left(\frac{zs}{E}\right)^2$

If there's part of this you do not understand, please ask specific questions about it.

Unky, it is derived from what was being done in that other thread, yes.

morgaine300 · Oct 25, 2009, 01:58 AM

I assume you have more information for that problem somewhere?

quizzman123 · Oct 25, 2009, 06:24 AM

Originally Posted by morgaine300

I assume you have more information for that problem somewhere?

Thanks, Morgaine300 for your answer. This was what I was looking for.

Thanks anyway, adam_89 and Unknown008 for your attempts.

Morgaine300, just with the info that I provided in my question, can I get the sample size of the population... i.e. population size 10,000 and Confidence Level 80%.

Can I assume a value for sigma or s, and for E?

quizzman123 · Oct 25, 2009, 09:17 PM

This is the scenario:

The total no. of calls that a call center receives (that is attented to by the Customer Service Reps) in a day is 1,000. There is also a team of Quality Analysts (10 members), and this team audits the calls taken by the Customer Service Reps.

Since it is impossible for the Quality Analysts team to audit every call, we need to take a sample size that has a Confidence Level of 80%.

How do we obtain the sample size?

morgaine300 · Oct 25, 2009, 11:47 PM

Hmm... I'm not really sure what that is. The 1000 calls a day thing almost sounds like a Poisson, but that's something I'm very unfamiliar with so I'm not even sure of that, let alone what to do with it. The confidence levels I've done have all been with normal distributions. Sorry.

Hopefully someone else knows what this is.