Unit 4: Continuous Probability Distribution
Definition:
Probability Density Function:
-Density Curves
-On or above the horizontal axis
-area underneath is exactly 1
-median is equal areas point
Normal Curves
-Area under each curve is the same
-Height of a normal distribution can be specifies mathematically in terms of two parameters
-the mean and standard deviation
-inflection points: changes from concave down to up, most flat part on curve
-within means on both sides
Empirical Rule:
Standard Normal Distribution: mean=0, standard deviation=1
-68% of the observations fall within 1s of the mean
-95% of the observations fall within 2s of the mean
-99.7% of the observations fall within 3s of the mean
-used to estimate
Percentiles:
-a percentile is the area under the curve to the left of the value in the data set
-in a normal curve the 50th percentile is located at the peak of the curve which is also where the mean is located
Z-score: standardized score, measuring spread of distribution using standard deviation
- round to the100th place
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