How to calculate Samples Size Proportions

Introduction on how to calculate samples sizes from proportions. Describes the relationship of sample size and proportion.

[skibumanne]

How do you knowwhat the standard deviation is going to be if you haven't yet done the study?

[manojinbox]

could you pls make it clear when you say that 'truth be told' and keep an eye on sd?

[statisticsfun]

The error rate is the level of error that the researcher is willing to live with. If you are doing statistics problems for class it is usually given.

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[statisticsfun]

The alpha in this case would be 1.96 to represent 95%.

[TokenFun]

Thank you, I think I'm just confused between error rate and alpha of 0.05...I though that was the error rate that 'most' statisticians are comfortable with.

[TokenFun]

where do you get the error rate from?

[statisticsfun]

@skibumanne That is another great question. If you know the standard deviation of the population you would use that... truth be told ... if you don't you keep an eye on your standard deviation and at some point it would stabilize (same with your mean).

[helenemeylemans]

what if you don't have a given SD?

[stevenyambaka]

how do you arrive at the proportion 0.1

[statisticsfun]

Not exactly sure what you are talking about.