Stats Unit 1

left vs right skew

right skew is when tail goes to right left is when tail goes to left

how to make a box plot

• you HAVE to find fences

• use whatever is lowest, min or lower fence, and whatever is highest, max or upper fence

• anything outside of that is an outlier

can you use 68 rule for skewed data

no bc it doesnt fit normal curve

what to remember abt 5 W’s

read carefully about the why. there’s usually smth more specific than “to gather data”. oftentimes this will lead to another question about whether the data is biased or not. 

why wouldn’t 5 num summaries and measures of central tendency make sense for the meat codes problem

it’s categorical

the name of a data piece is categorical or quantitative

considered an “identifier” 

when to declare vars independent or associated

72 and 79 is associated, those are different enough. if it was 72 and 73 then sure maybe no association.

what charts can / can’t be over 100%

• pi charts cannot

• bar charts can 

no matter how small, what changes if you add an outlier 

range 

when just looking at a graph, what measure should you NOT mention

standard deviation

is a likert scale quantitative or categorical?

categorical

how to find independence

compare sets of conditional distributions. find the percentages of all data in reference to a category’s total (conditional). then compare within each category, between two categories, to see if there are associations. if everything is relatively the same, then there is no association. if there are patterns that show the percentages are changing according to one variable being changed, then there is an association. 

how to compare conditional

do not compare conditional to marginal. compare conditional to conditional. in this example, both were similar enough to marginal but that’s not what you should be looking at. cuz conditional was quite different from each other, as first borns more likely to do math and 2nd borns more likely to do humanities. that difference is association. 

how to do stem leaf plot with 3 digits

to keep 5-15 bins, you can include a range for one number. like 6/2 could represent 620 - 629.