Module 2 - Symmetry, Variability and Presentation Flashcards
What is a Symmetric Distribution?
A symmetric distribution is a type of probability distribution where the left and right sides of the graph are mirror images of each other, with the mean, median, and mode all occurring at the center.
What is a Positively (right) Skewed Graph?
What is a Negatively (left) Skewed Graph?
How to tell whether the data distribution is symmetric?
* Skewness statistic
* Histograms (and density plot)
* Boxplots
Symmetric distribution: Skewness = 0
Left/Negatively skewed: Skewness = < 0 (negative numbers)
Right/Positively skewed: Skewness = > 0 (positive numbers)
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Would this be left or right skewed?
Left/Negatively Skewed because there is a longer whisker on the left (lower values) and the outlier is on the lower end
Furtheremore, In left-skewed distributions, the median tends to be closer to the top of the box, as seen here.
How do we know these are Normal distributions?
Unimodal and Symmetrical
What is Kurtosis?
Tailedness of the Distribution
Whether tails are light or heavy
What is a Heavy Tail?
A Tail is heavy when it contains outliers
An outlier has more influence in the kurtosis statsistic
Thus they have more “weight” on the kurtosis, thus heavy
What is a Light Tail?
A tail is light when it is less likely to have outliers
Kurtosis = 0
Kurtosis > 0
Kurtosis < 0
What do Kurtosis Values tell us?
Boxplot is better at seeing outleirs
How should you add tables to your reports?
How should you add graphs to your reports?
