STP 420 Midterm 1

Formulas/ Notes for STP 420

It contains the following values when looking at data:
1. Minimum
2. Quartile 1
3. Quartile 2
4. Quartile 3
5. Maximum

What is the 5 number summary? What does it contain

Quartile 3 - Quartile 1

How do you get the Interquartile range?

Lower Limit = Quartile 1 - 1.5 ( IQR)
Upper Limit = Quartile 3 + 1.5 (IQR)

How do you determine if something is an outlier?

If it’s odd, find the middle value. If its even, find the two values in the middle, add them up, divide them by 2.

How do you find median?

Count up all the values in the dataset and divide it by the amount of data there is.

How do you find mean?

Maximum - Minimum

How do you find mode?

A variable that records the amount of something

What is a quantitive variable

Height

Which of the following is an example of a quantitive variable

A variable that records which of several

categories a person or thing is in.

What is a categorical variable?

Hair color

Which of the following is an example of a categorical variable?

A variable with a finite number of possible values

What is discrete variable

A variable with an infinite number of possible

values

What is a continuous variable

A distribution with one peak

Unimodal distribution

A distribution with two peaks

Bimodal distribution

A distribution with two or more peaks

Multimodal distribution:

A distribution that has a longer left tail

Left skewed distribution

A distribution that has a longer right tail

Right skewed distribution

Standard Deviation

Boxplot graph

1. Always ON or ABOVE the HORIZONTAL LINE

2. Total area under the density curve is always equal to 1

Facts about the density curve

Something to help us understand how many standard deviations are above/below the mean at a particular value

Z-score

Z = X-Mean/Standard deviation

What is the Z-Score formula

Z scores have a mean of 0 and a standard deviation of 1
They have a typical range of -3 to 3

What are some facts about the Z-score

It needs to have a value with the frequency of 2 (appears twice).

What is required for something to have mode?

It has the mean and median of equal value. However that doesn’t mean that the mean and median can represent a symmetrical distribution if we didn’t have a graph.

What is true about the symmetric distribution