High School Mathematics - 2 11.9 Normal and Skewed Distributions
Normal and skewed distributions:
The probability distributions we studied so far are discrete probability distributions because they have only a finite number of possible values.
A discrete probability distribution can be represented by a histogram.
For a continuous probability distribution, the outcome can be any value in an interval of real numbers.
Continuous probability distributions are represented by curves instead of histograms.
Such curves are often called a bell curve.
Many distributions with symmetric curves or histograms are normal distributions.
In normal distributions scores are more concentrated in the middle than in the tails.
A curve or histogram that is not symmetric represents a skewed distribution.
Positive skew: The right tail is longer and the mass of the distribution is concentrated on the left of the figure. The distribution is said to be right-skewed.
Negative skew: The left tail is longer and the mass of the distribution is concentrated on the right of the figure. The distribution is said to be left-skewed.