15 terms

density curve

A curve that describes the overall pattern of a distribution.

• is always on or above the horizontal axis

• has area exactly 1 beneath it

• is always on or above the horizontal axis

• has area exactly 1 beneath it

µ (mu)

mean of distribution

σ (sigma)

standard deviation of a density curve

outcomes

The results of a chance experiment

simulation

Pretending to perform a chance experiment and coming up with fictitious but possible outcomes.

normal curve

Curves that are symmetric, single-peaked, and bell-shaped

normal distribution

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.

inflection point

The point at which a change of curvature takes place

68-95-99.7 rule

• 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

• 95% of observations fall within 2 σ of the mean µ

• 99.7% of observations fall within 3 σ of the mean µ

percentile

The percent of the distribution that is at or lower than the observation

N (µ,σ)

normal distribution (with mean µ and standard deviation σ)

standardized value

(x-µ)/σ

observation (x) - mean (µ)

-----------------------------

standard deviation (σ)

observation (x) - mean (µ)

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standard deviation (σ)

z-scores

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