PSAT mid term

Quantitative variables

Expressed as numbers

Categorical

In categories not, numbers

Distribution is

The values a variable can take on

What is range

Range = maximum - minimum

What is the sample median

The middle number of data set (set is in numerical order)

How do you find the IQR

Find the overall median, then the median of the lower half of data (q1) then find median of upper half of data(q2). Then calculate for IQR. IQR=Q3-Q2

What would happen to the IQR if a student's travel time of 35 minutes was mistakenly entered as 65 minutes?

Nothing, the median of the data set would not be affected

Box plots don’t show…..

Distribution of data

to calculate the mean…

Add all the numbers of the data set, and divide by the amount of data points

What is the standard deviation

How much a point departs from the mean

Deviation=

Data point - mean

S is

The sample standard deviation

N is

Sample size

To describe a distribution you need to use SCOS. What does SCOS stand for

S is shape/ modes and symmetry. O is outliers. C is center/ using mean for symmetric data and meadian for skewed data. S is spread/ standard deviation for symmetric data and IQR for skewed data

_

X

Is the mean statistic notation

Bi-modal

Means there’s two different sections in the data

Unimodal

Data is all in one group

What direction is the skew

Left

The graph is skewed…..

in the direction that has the longer tail

A parameter is

The entire population (all of ucsb students)

The mean parameter notion

Standard deviation parameter notion

Variance parameter notion

Mean statistic notion

Standard deviation Statistic notion

Variance statistic notation

Explanatory variable might effect ________

Response variable

Random assignment is

Casual

Random sampling is

Generalizable

SRS is

Random sampling

SRS means that everyone in the population

Has an equal chance of being selected, the resulting sample is representative of the population

• Stratified Sampling:

• Divide the population into groups (strata) and sample within each.

• Multistage Sampling:

• Combine clustering and individual sampling.

p

population proportion

^

p

sample proportion

the null always assumes

nothing special is happing

null is denoted by

Ho

the alternative hypothesis is denoted by

Ha

a normal distribution is shaped like a

bell

describes….

the spread/ variability of the distribution

specifies….

the center of distribution

a z-score is also a

standard score, aka a standard deviation

the z- score formula is

x - u

—-

o