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14 Cards in this Set
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Internal Quartile Range=
IQR = Q3Q1 Determining Outliers Q3 + 1.5 * IQR Q1  1.5 * IQR 
For Calculator
STAT>(CALC) 1:1Var Stats (Data must be enter in L1/L2) 

Density Curve
Always on/above horizontal axis. Area of exactly 1 underneath. 
Density Curve Drawings


689599.7 Rule
68% of observations within 1 standard deviation. 95% of observations within 2 standard deviations. 
99.7% of observations within 3 standard deviations.


ZScore
z=(xU)/o U is mean population. o is standard deviation. x is observed. 
To find the area to the left of the z score uner the standard normal cure use table a then find z score on table number that corresponds to z score on the table= area under curve to left of the z score


Working w/Interval
ex:What % of 14 year old boys have a blood cholesteral level between 170240 mg/dl U=170 O=30 ? 
Step1: State the problem We want the proportion of boys with 170<x<240
Step2: Standardize + draw a picture. 240170/(30)=2.33 

Working w/interval
Step3: USETABLE. The area below 2.33+0 is the area below 2.33 minus the area below 0. .9901.5=.4901 
Picture Interval


Step4: STATE YOUR CONCLUSION IN CONTEXT: about 497 of boys have cholestral levels between 170240 mg/dl.

Finding a value given a proportion.
ex: Scores on the SAT Verbal test in recent years follows approx. the N(505,110)=(N(U,O) distribution. How high must a student score to be in the top 10% of all students taking the SAT? 

Finding Value given a proportion
Step1: State Problem + Draw Sketch We want to find the sat score x with area .1 to its right under the normal curve with mean U=505 and standard devition O=110 thats the same as finding the SAT score x with area .9 to its left. 
Step2: USE TABLE Look in the body of TABLE A for the entry closest to .9. It is .8997. This is the entry coresponding to z=1.28. So z=1.28 is the standardized value w/area .9 to its left.


Step3: UNSTANDARDIZE to transform from the z back to the orginal x scale. We know that the standardized value of the unkown x is z1.28. So x itself satisfies.
(xU)/O = z (x505)/110=1.28 Solve for x. 
Finding area with Calc
Graph: 2nd Vars(DIST) then choose Draw and 1:Shade Norm(lower#,higher#,U,O) press Enter No graph: 2nd Vars (Distr) choose 2:normalcdf(lower#,higher#,U,O) 

Finding Z Value on calc
2nd VARS (Distr) 3.: invnorml(area to left,U,O) ENTER gives you x value invnorml(.9) gives you z value 
Chapter 3 Scatter Plots
response variable measures outcome of study. explanatory variableattempts to explain the observed outcomes. Scatter Plot shows the relationship between two quantitative variables measured on the same individuals 

Examining A Scatter Plot
Form: Linear Relationships where points show a straight line pattern are an important form of relationship between z variables. Curved Relationships + Clusters are other forms to watch for. 
Direction= If the relationships are positively/negatively associated.
Strength= Strength of relationship is determined by how close the point in the the scatterplot lie to a simple form such as a line. 

Chapter 4
Linear= Exponentional= Power= 
Linear


Linear

Exponential


Exponential

Power
