Unit 1 Good To Knowt

Frequencies =

Count

Relative Frequencies =

Percent

When should bar graph/ segmented bar graph should be in relative frequency?

When sample sizes are different

What should always be there when drawing graphs?

X- Axis, Y- Axis, and Title labeled; Scale; Legend (if needed)

Marginal Relative Frequency

Row/Column over Total

Joint Relative Frequency

Row and Column intersection

Conditional Relative Frequency

Given row/column

Individual bars must add to 100% in Relative Frequency; Association and Conditional

Segmented Bar Graph

Used with different sample sizes

Mosaic Plots

Categorical sees how variables vary with

Association

Pictographs, Scale not at (0,0), bar graphs relative frequency adding to more than 100%

Misleading features of graphs

What should you do with any questions or graph in general?

Read it carefully

Association does not mean

Causation

Stem and Leaf Plot Important point

Do not forget the key 5I0 = 50

Shape

-ly (if mean and median are close but not equal) followed by skew L/R, symmetry, or uniform

Outliers

Calculate (Q1/Q3 +/- IQR(1.5))

Variability

How something varies from to, range, IQR

Center

Mean- symmetrical; Median- Skew

In any FRQ problem

put CONTEXT

Only use unimodal, bimodal, multimodal for

number of peaks and only if you really think it is necessary

When comparing distributions always use

greater/less than vocabulary

5 Number Summary

Min, Q1, Median, Q3, Max

Range is used when the distribution has

no outliers

IQR is used when the distribution has

outliers and skew

STDev is used when the distribution is

symmetrical

Why isn’t variance used by statisticians?

While it is the correct interpretation for how much something spreads from the mean, it is used in incorrect units, square.

What are the dots, bars, line 1 of the box, line 3 of the box, and the middle line of the box in a box plot?

Outliers, Min and Max, Q1 and Q3, Median

Just for FRQ purposes, what should you always do for center and variance?

Use median and IQR

Stem/Dot plot strength and weaknesses

Shows shape and individual data but inefficient for larger sets of data

Histogram strength and weakness

Shows shape and efficient for large sets of data but does not show individual data pieces

STDev Formula for Outliers

Mean ± 2(STDev)

Which two are resistant to change from outliers?

Median and IQR

Lower IQR =

More consistent data

When given data be sure to:

List from least to greatest

On MCQ for shape questions, make sure to look for a _____ unless you are positive it is ______

-ly word; exactly

Only answer relative frequency when it is compared on

a single segmented bar graph

In a question where mean is calculated and a student left, consider that it may be (since for example an average of 85 for 5 students, one with a 98 leaves so would the mean become less?)

cannot be concluded (no because the remaining 4 may still average 85)

Be careful about word choice because

if a question is a definite yes, be confident in answer, otherwise if the answer definitely is vague only then put -ly words