H1H1 H1H1 HoHo Z = 0 Two Tailed test

Z score where 2.5% of the distribution lies in the tail: Z = Critical value for a two tailed test.

85 5% One tailed test

85 5% One tailed test

Z score where 5% of the distribution lies in the tail: Z = Critical value for a one tailed test.

Z scores require  and  What happens when the population mean is known but the standard deviation is unknown?

T test for single samples

is the standard error of the mean, estimated.

S is representing the standard deviation of the sample, as an estimate of the population.

n - 1 represents degrees of freedom. (df) Degrees of freedom: the number of values that are free to vary.

Computational Formula Standard deviation of a sample as an estimate of the population.

Situation that calls for a t test for single samples: 1) Population mean is know n. 2) The standard deviation of the population is unknown. 3) A sample of a specific size is available.

Steps for a single sample t test: 1) compute the standard deviation as an estimate of the population. 2) compute the standard error estimated 3) compute t 4) evaluate the computed t value to determine if it is statistically significant.

The t distribution: - Symmetric - Flatter middle than a normal distribution. Fatter tails.

Critical value = 2.262