# What is the Appropriate Sample Size for a Customer Survey?

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#### biboy2012

If we have 8,000 active accounts/customers, how many customers need to survey? What is the recommendation of statistical textbooks?

#### Jim Wynne

Re: Customer survey....random by how much?

If we have 8,000 active accounts/customers, how many customers need to survey? What is the recommendation of statistical textbooks?

You might find this brief paper (PDF) helpful. It includes a table for determining sample sizes.

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#### biboy2012

Hi Jim,
Thanks for the excellent reference/attachment. I have a very little knowledge of statistics that's why I found this a little bit harder.

Let me give you an update. We conducted customer survey using two channels, e-mail and walk-in. We are on our third week but very few responses. From your attached file I refered to the table to determine the recommended sample size. Since there are 8,000 active accounts/customers, the recommended sample size for categorical data could be 262 or 367 or 613. My question is this.. Should I stop at 262 or 367 or 613 samples even if the response is low? Or should I continue conducting surveys until we reached 262 0r 367 0r 613 responses?

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#### alekra

Dear All,

In the company I work for, we´re used to make an ABC analyses (based on \$\$\$ return/sales). We concentrate our efforts in performing a survey with A anb B customers (considering that they contribute more).

Regards!

Alekra

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#### ASQ girl

Hi, if you have Minitab go to graphs, the power (last option), sample 1 T and enter the info it will give you the calc. In order to do this you need to have the mean, std dev , for the power use 0.99. It helps.:

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#### Murphys Law

I would understand the customer base a bit more and find out how your sales / marketing group assess your customers.

Do they arrange them into big accounts? Are they grouped by revenue - major accounts, medium accounts, small accounts serviced through distributors ? Are the grouped geographically?

Also what do you want to do with this data? Are you wanting to grow business? How much of the business is repeat business regardless?

Knowing this you can target who you survey and what you ask them. Get your sales force involved in this. This can be a sales tool for them as well.My experience is sales are pretty protective of their customers and they are leary of some QA clown going in and talking to their customers.

I don't know about you but I have customer survey fatigue in the commercial world. Surveys by car manufacturers for example, are skewed by the sales person pre-checking how I am going to answer as their compensation may be based on this.