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14 Cards in this Set

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Internal Quartile Range=
IQR = Q3-Q1
Determining Outliers
Q3 + 1.5 * IQR
Q1 - 1.5 * IQR
For Calculator
STAT---->(CALC)
1:1-Var Stats
(Data must be enter in L1/L2)
Density Curve
Always on/above horizontal axis.
Area of exactly 1 underneath.
Density Curve Drawings
68-95-99.7 Rule
68% of observations within 1 standard deviation.
95% of observations within 2 standard deviations.
99.7% of observations within 3 standard deviations.
Z-Score
z=(x-U)/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 170-240 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.
240-170/(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 170-240 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 z-1.28. So x itself satisfies.
(x-U)/O = z (x-505)/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 variable-attempts 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