How to find a standard deviation
Find the mean of the sample size
Find the individual deviations ( I equals position in the data set)
Square the individual deviations
Sum the squares of the deviations
Divide the sum of the squares of the deviations by n-1 if it is a sample, devide by n if it is a population. There is no need to adjust for the degree of freedom if you have the entire population and not just a sample.
Standard deviation is = the square root of the variance.

Lecture notes
Statistics come from samples and parameters come from populations. s goes with s and p goes with p.
Qualitative doesn’t have numbers (labels not numbers). Quantitative has to do with numbers.
Census is entire population sample is part. Take a sample when it is not practical to take a census.
Random sampling is simply random, systematical sampling is when there is a pattern when choosing the sample (systematic approach). Cluster sample is when you sample everything in a randomly selected sample (divide into groups and sample everything in a selected group). Stratified sample is when you divide samples into groups and you select small samples from multiple groups that are the same size. Convenience sample is when little effort is given to find a quality sample, and the offer the worst data.

Levels of measurement. Noir. Nominal you cannot rank. Ordinal you can rank but they are subjective, no real numerical value. Interval is a number, numerical values that do not have a real 0,