1. Population Proportion
The fraction of values in a population which have a specific attribute
 = X / N
 = Population proportion
X = Number of items having the attribute
N = Population Size

2. Sample Proportion
The fraction of items in a sample that have the attribute of interest
p = x / n
p = Sample proportion
x = Number of items in the sample with the attribute
n = Sample size

3. Sampling Distribution of Proportion
In many instances, the objective of sampling is to estimate a population proportion. In all instances, the decision makers could select a sample, compute the sample proportion, and make their decision based on the sample results. If the sample size is sufficiently large, the normal distribution can be used as a reasonable approximation to the discrete binomial distribution.

4. Sampling Distribution of p
Provided we have a large enough sample size, all the possible sample proportions will be approximately normally distributed with
p= 
Standard Error = p = SQRT[ (1 -  ) / n]