PS296 Lecture Notes - Lecture 4: Normal Distribution, Unimodality, Standard Deviation
Normal Distributions:
-distribution that forms a bell-shaped curve
-Vertical axis = density, frequency of scores at each value
-Horizontal axis = value of scores
Properties of normal distributions:
-form a symmetrical bell shaped curve
-unimodal
-50% of data fall below the midpoint and 50% of data fall above the midpoint
-the curve is asymptoptic (tails never actually touch the x value)
-the median, mean, and mode are located at the midpoint of the curve
-the curve is denser in the centre than in the tails (more data in the centre of the
distribution)
-shape is defined by the mean and standard deviation
-the total area under the curve is equal to 1.00 (curve divided into 4 percentiles, all
equaling to 100)
-the shape of a normal curve is influenced by the variance of the distribution (flattens,
more narrow)
-the location of the centre of a normal curve is dependent on the mean of the distribution
(shifts it back and fourth/to the left or right on the x axis)
Document Summary
Vertical axis = density, frequency of scores at each value. 50% of data fall below the midpoint and 50% of data fall above the midpoint. The curve is asymptoptic (tails never actually touch the x value) The median, mean, and mode are located at the midpoint of the curve. The curve is denser in the centre than in the tails (more data in the centre of the distribution) Shape is defined by the mean and standard deviation. The total area under the curve is equal to 1. 00 (curve divided into 4 percentiles, all equaling to 100) The shape of a normal curve is influenced by the variance of the distribution (flattens, more narrow) The location of the centre of a normal curve is dependent on the mean of the distribution (shifts it back and fourth/to the left or right on the x axis) The shape of a normal curve is influenced by the size of your sample.
