NORMAL CURVE Needed for inferential statistics. Find percentile ranks without knowing all the scores in the distribution. Determine probabilities.
Characteristics of Normal Distributions symmetrical equal mean, median, and mode bell-shaped
Why Be Normal? Many variables are assumed to be normally distributed. Why? Most variables are affected by many random factors. Because the factors are random, their effects tend to balance out.
Areas Under the Normal Distribution We can find a proportion of scores above or below a particular point in the normal distribution. This proportion can be interpreted as a percentage, or as a probability. We don’t need to know all the scores.