ECO-2100 Lecture Notes - Lecture 3: Skewness, Frequency Distribution, Unimodality

46 views2 pages
9 May 2017
School
Department
Course
Professor
Eco 2100 Chapter Three notes
A histogram is a graphical representation of a frequency distribution.
The Y-axis of a histogram shows the frequency or percentage (relative frequency) of each bin
Shape:
Modal Class: a histogram bar that is higher than those on either side
Unimodal, bimodal, trimodal, multimodal
Modal classes may be artifacts of the way bin limits are chosen.!
Skewness: the direction of the longer tail of a histogram.
Left skewed - (negatively skewed) a longer left tail
Right skewed - (positively skewed) a longer right tail
Symmetric - both tail areas are the same
Two ways to determine the skewness of the distribution of all data values in a sample
One: plot a histogram
Two: compare the mean, median, and mode
Mode>Median>Mean - skewed left (Mode is largest)
Mean=Median=Mode - symmetric
Mode<Median<Mean - skewed right (Mean is largest)
Chapter Four Notes
Mean:
The mean is the balancing point
In Excel, use the function AVERAGE(Data)
Median:
The median is the midpoint of a sorted sample data.
If n (sample size) is odd, the median is the middle observation in a sorted data array.
If n is even, the median is the average of the middle two observations in a sorted data array
In Excel, use the function MEDIAN(Data)
Median vs. Mean
Median is very stable compared to mean
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows half of the first page of the document.
Unlock all 2 pages and 3 million more documents.

Already have an account? Log in

Get OneClass Notes+

Unlimited access to class notes and textbook notes.

YearlyBest Value
75% OFF
$8 USD/m
Monthly
$30 USD/m
You will be charged $96 USD upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.