The observed difference divided by the expected difference in a single score from a sample or population.
Reverse z score
to get a sample score from a z-score
Standard Error of Mean
Indicates the amount the sample mean will deviate from the population mean.
As N gets bigger the SEM gets smaller.
Larger samples estimate the population mean better.
Larger samples = Lower standard error of mean
The chi-square test is used when dealing with nominal data.
Where O is the observed frequency in each cell, E is the expected frequency in each cell, and the symbol sigma refers to summing over all cells.