Parameter Estimate and Statistics

Data description

Dot plot, frequency table, histograms

Central tendency

Middle value (mean, x|)

Dispersion (spead)

Standard deviation(s), how far from center data tends to range

Z-score

How many standard deviations is a data point away from the mean

Zi = (xi-x|)/s

Proportion of any area under the curve for any normal distribution =

Proportion of the area between the corresponding z-scores in z-distribution

Central limit theory

Behaviors usually follow normal distribution (bell curve)

Parameter estimation

Compute an interval around sample mean, x| that will include the population parameter with certain probability (usually 95%), using sample information and confidence interval

mu

mean of population

lowercase sigma

standard deviation of population

x|

mean of sample

s

Standard deviation of sample

mu_x

Mean of sample mean distribution

lowercase sigma_x

Standard deviation of sample mean distribution

Confidence interval

A range with an upper and lower bound, with sample mean in middle

Confidence interval equation

x| +- Z_a * S_x|

where S_x| = s/root(n) (standard error)