Highlighted memory

Question 1

FIve Number summary

Answer 1

Min, Q1, Med, Q3, Max

Question 2

Describing or comparing distributions

Answer 2

For quantitative data discuss

shape center spread outliers

Question 3

Outlier

Answer 3

An extreme observation is an outlier if it is smaller than Q1-(1.5IQR) or larger than Q3+(1.5IQR)

Question 4

Choosing Measure of Center and spread

Answer 4

The mean and standard deviation are used to compare roughly symmetric distributions. The median and IQR are used to compare distributions where at least one is skewed, because they are resistant to outliers and skewness

Question 5

percentile

Answer 5

Percent of the distribution that is below the value of that distribution

Question 6

Z-Score

Answer 6

How many standard deviations x lies above or below the mean

Question 7

Density curve

Answer 7

A density curve always
remains on or above the horizontal axis
has total area 1 underneath it

Question 8

Describing scatterplots

Answer 8

discuss

direction form strength outliers

Question 9

residual plot

Answer 9

when the residual plot has no obvious pattern, the linear model is appropriate for the actual data
when the residual plot has an obvious pattern, the linear model is NOT appropriate for the actual data

Question 10

S:

Answer 10

Standard deviation of the residuals, the typical size of the prediction errors (residuals) when using the regression line, in context

Question 11

r^2

Answer 11

Coefficient of determination: r^2 percent of the in variation in y is accounted for by the least squares regression line relating x to y, in context

Question 12

4 basic principals of experimental design

Answer 12

Comparison: Use a design that compares two or more treatments
Random Assignment: Use chance to assign experiment units to treatments. This helps create roughly equivalent groups before treatments are imposed
Control: Keep as many other variables as possible the same for all groups. Control helps avoid confounding and reduces the variation in responses, making it easier to decide whether a treatment is effective.
Replication: Impose each treatment on enough experiment units so that the effects of the treatment can be distinguished from chance differences between the groups

Question 13

Statistically significant

Answer 13

When an observed difference in responses between the groups in an experiment is too large to be explained by chance variation in the random assignment

Question 14

scope of inference

Answer 14

We can infer about population if individuals taking part in a study were randomly selected from the population
We can infer about cause and effect if a well-designed experiment that randomly assigns experimental units to treatments is used

Question 15

Law of large numbers/probability

Answer 15

the law of large numbers says that the proportion of times that a particular outcome occurs after many repetitions will approach a single number, its probability

Question 16

independent

Answer 16

two events are independent when knowing the occurence of one event does not raise or lower the likeihood of the other event occuring
a and b are independent if P(A|B)=P(A)

Question 17

mean of a discrete random variable

Answer 17

also called the expected value. After repeating many trials, the expected value is the average value of the outcome per trial (in context)

Question 18

Standard deviation of a discrete random variable

Answer 18

the typical distance that each trial’s outcome is from the mean value in context

Question 19

Mean and standard deviation of a sum of random variables

Answer 19

for any two random variables x and y, if s=X+Y
E(s)=Ms=Mx+My
os^2=ox^2+Oy^2, or equivalently Os={Ox^2+Oy^2}
THe sum of independent Normal random variables follows a normal distribution

Question 20

Mean and standard deviation of a difference of random variables

Answer 20

For any two random variables X and Y, if S=X+Y
E(S)=Ms=Mx+My
Os^2=Ox^2+Oy^2 or equivalently Od={Ox^2+Oy^2}
The difference of independent normal random variables follows a normal distribution

Question 21

Binomial setting

Answer 21

consists of fixed n independent trials of the same chance process, each resulting in a success or a failure, with probability of success p on each trial. The 4 conditions are BINS
Binomial
Independent 
Number of trials fixed
success probability fixed

Question 22

Geometric setting

Answer 22

consists of repeated trials of the same chance process in which the probability p of success is the same on each trial, and the goal is to count the number of trials it takes to get one success