# Statistics

The online open educational resources(OER)

## Mean, Variance and Standard Deviation

• Population Mean and Sample Mean
• Variance and Standard Deviation (Population or Sample)

Mean: The mean of a data is the sum of the data entries divided by the number of entrie.

Standard Deviation: In mathematics and statistics, deviation is a measure of difference between the observed value of a variable and some other value, often that variable's mean. The standard deviation is a non-negative number that measures how far data values are from their mean.

Variance: The average of the "squared" differences from the Mean.

## More example: Finding the standard deviation using the definition formula (Luis Cruz)

Frequency Distribution: The frequency distributions are helpful for computing the mean and standard deviation.

## More example: Standard deviation calculated using a frequency table with midpoint(Luis Cruz)

The Computational Formula: The Computational(Computing) Formula helps if data are not whole numbers and the mean is not one decimal.