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10 Cards in this Set

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  • Back
Imp point
Many histograms are bell-shaped symmetric--these are modeled with a density curve called a normal distribution.
Characteristics of a Normal Distribution
3.One peak
Notation for Normal Distribution
1.Mu=point of symmetry of normal distibution
2.Sigma=distance from the mean to the point where the curve begins to fall less steeply
3.Behind the mean we do:mu-sigma.
4.After the mean we do:mu+sigma (mu)
It is the distance from the mean(mu) to the point where the skier begins to decelerate. (see graph on CD)
Animtion of Normal Distribution of changing MU
1.If zero then it is symmetric
2.if mu>0 then graph moves on x axis to the right
3. If mu<0 then graph moves on x axis to the left
Animtion of Normal Distribution of changing SIGMA
1. Increase sigma then the graph's base covers more area on the x axis and it widens
2.Decrease sigma then the graph becomes thinner
Importance of Normal Distribution
1.Describes many distributions of real data and "chance" outcomes
2.Models many roughly sumetric distibutions for statistical inference
Normal Distribution Areas
68% of data lies within 1 of the mean
95% of data lies within 2 of the mean
99.7% of the data lies within 3 of MEAN
Percentage of Area within intervals
1.Subtract by previous percentage and then divide by half to get the area between tha particular interval
Cumalative Area Percentages
1.Add from left to right
2.It is the values that lie to the left of the values that the amount of percentages cover.