AP Statistics : Chapter 2 - The Normal Distributions (Vocabulary)
A curve that describes the overall pattern of a distribution.
• is always on or above the horizontal axis
• has area exactly 1 beneath it
mean of distribution
standard deviation of a density curve
The results of a chance experiment
Pretending to perform a chance experiment and coming up with fictitious but possible outcomes.
Curves that are symmetric, single-peaked, and bell-shaped
Described by a normal curve in which the mean is located at the center of the symmetric curve and is the same as the median.
The point at which a change of curvature takes place
• 68% of the observations fall within one σ of the mean µ
• 95% of observations fall within 2 σ of the mean µ
• 99.7% of observations fall within 3 σ of the mean µ
The percent of the distribution that is at or lower than the observation
normal distribution (with mean µ and standard deviation σ)
observation (x) - mean (µ)
standard deviation (σ)
another name for standardized value; tells us how many standard deviations the original observation falls away from the mean and in which direction.
standard normal distribution
the normal distribution with mean 0 and standard deviation 1
normal probability plot
method of providing a good assessment of the adequacy of the normal model for a set of data