Midterm Review

Question 0

Area under density curve

Answer 0

Always = 1

Question 1

How to tell if something is an outlier

Answer 1

Q1 - 1.5(IQR)
Q3 - 1.5(IQR)
Outside of this range is an outlier

Question 2

Density Curve

Answer 2

A smooth curve which approximates the shape of a histogram and describes the overall pattern of a distribution

Question 3

Residual

Answer 3

The difference between an expected value and the actual value (y-yhat)

Question 4

Complementary events

Answer 4

When two events together make up the entire sample space (even and odd numbers)

Question 5

Ogive graph

Answer 5

Graph of percentile, relative cumulative frequency distribution

Question 6

Variance calculation

Answer 6

Σ(x-xbar) squared / (n-1)

Question 7

Independent event

Answer 7

Choice of selecting one object does not affect ways of selecting other objects

Question 8

Dependent events

Answer 8

Selecting an object does affect selecting other objects

Question 9

Circular permutations

Answer 9

N objects in a circle, then (n-1)! permutations of the objects

Question 10

Calculating correlation

Answer 10

Sum (standardized x)(standardized y) / (n-1)

Question 11

Least squares regression

Answer 11

Method of predicting response given explanatory
Line of “response” on “explanatory”
LinReg(a+bx)
Yhat= a + bx

Question 12

LSRL “b”

Answer 12

Slope:

r(sy/sx)

Question 13

LSRL “a”

Answer 13

Intercept:

Ybar- b(xbar)

Question 14

Coefficient of determination

Answer 14

R^2,

Percent variation that can be explained by the lsrl

Question 15

Influential point

Answer 15

When removed, dramatically changes slope of lsrl, often x outlier

Question 16

Power law model

Answer 16

Y=ax^p
Log y = log a + p log x
Both variables are transformed

Question 17

Exponential growth model

Answer 17

Y=ab^x
Log y = log a + x log b
Only response is transformed

Question 18

Common response

Answer 18

A lurking variable- both x and y are acted on by another z force

Question 19

Confounding

Answer 19

A lurking variable which also affects the response, making it unclear how much effect the explanatory actually has

Question 20

Conditional distribution

Answer 20

Table cell/row or column total

Question 21

Marginal distribution

Answer 21

Sum or row total/table total

Question 22

Important in experiment design

Answer 22

Control (lurking variables)
Random (SRS)
Replication of experiment

Question 23

Observational study

Answer 23

No treatment/experiment

Question 24

Multiplication rule

Answer 24

If events a and b are independent, then p(a)p(b) = p(a and b)

Question 25

Random variable

Answer 25

Variable with numerical value

Question 26

Continuous random variable

Answer 26

Each individual outcome has p=0, use a normal distribution

Question 27

Discrete random variable

Answer 27

Has a finite # of values, each value has a probability

Question 28

Variance of discrete random variable

Answer 28

Sigma^2 sub x = Σ(x-μ)^2(p)

Question 29

Mean of discrete random variable

Answer 29

μx = Σ(xp)

Question 30

Means of random variables

Answer 30

μ(a+bx)= a + b μx
μ(x+y) = μx + μy

Question 31

Variance rules

Answer 31

Sigma^2sub x+y = sigma^x + sigma^2y + 2ρsigmaxsigmay

Sigma^2x-y= the same but - 2ρsigmaxsigmay
Where ρ is the correlation

Question 32

Rule of thumb for a binomial distribution

Answer 32

Use a normal approximation when np is greater than or equal to ten, and n(1-p) is greater than or equal to ten

Question 33

Mean and standard deviation of a binomial distribution

Answer 33

Mean=np

Strd Dv= root (np(1-p))

Question 34

Stratified random sample

Answer 34

Divide population into strata, take srs from each stratum and combine for whole sample

Question 35

Blocking

Answer 35

In an experiment, group together those known to be similar, and apply each treatment to each block so that there arent confounding variables