Unit 2 Flashcards
What is distribution?
Shape, outliers, center, spread
What is the difference between frequency and relative frequency?
Frequency is the amount of counts (like to make a histogram) and relative frequency is the percentages of the whole
When is it better to use relative frequency?
When you’re working with a large data set
What types of graphs are appropriate for quantitative data?
Histograms, stem/leaf plots, dot plots, box plots
What is marginal distribution?
Takes percentages of the whole of a sample
What is conditional distribution?
Takes a percentage from only one variable of a sample
Do different or same calculated values imply an association?
Different
How is shape measured?
Symmetry, mode, skewedness
How is center measured?
Median or mean
How is spread measured?
Standard deviation, IQR, range
What does it mean for a value to be resistant?
It is not effected by outliers or extreme values
Which measures are resistant?
Median, IQR
What can increase the standard deviation?
Outliers or increased variability
Describe the shape if mean = median
Approx. normal or symmetric
Describe the shape if mean < median
Skewed left
Describe the shape if mean > median
Skewed right
How do you find a percentile?
Z-scores
Do z-scores have units?
No
What does the +/- tell you?
Direction of deviation
What measures change when adding/subtracting the same value to every score?
Median, mean
What measures change when multiplying/dividing by the same value to every score?
All are increased by x
What is the relationship between the point of inflection and standard deviation?
The point of inflection is where a bell curve slightly changes direction at the threshold of each standard deviation
When do you use InvNormal( ) ?
When you know the percent and are working backwards o find a z-score