Formulas
The average value describes what
Mean
Which of the following is a qualitative variable?
A) Hair color
B) Number of Blondes
C) Annual Salary
A) Hair Color
Find the mean of the following:
10, 15, 12, 21
Mean: 14.5
Geographic center for a set of features
Mean Center
An observation that is unusually distant from other observations
Outlier
The middle value of a list in ranked order
Median
Zoning category, Color, Vegetation type, and city name are all types of what data
nominal data
What is the median of the following set of numbers?
12, 8, 13, 4, 7, 6, 3, 15
Median: 7.5
The feature whose total distance to all other features is the shortest
Central Feature
Closeness of a measurement to the actual value
Accuracy
average squared deviation from the mean
variance
Ordinal data
Evaluate: 28 / 6 * 2
28/6 = 4.67
4.67*2 = 9.33
_____ indicates how locations or points deviate from the mean center or the spatial mean
Standard distance
How consistent the data are
Precision
average distance of data points from the mean
standard deviation
E. coli concentrations in flood waters are what type of data?
Ratio data
Values along a continuum where the values do have an absolute meaning
What is the coefficient of variation for a location with an average annual precipitation of 80 cm and a standard deviation of 7.
Express your answer as a percentage.
CV=s/x*100
7/80*100 = 8.75%
Population, Number of households, Area, Disease cases, Traffic volume, Pollutant emissions, and Employment are all examples of
possible weights
a distribution of data with a wider and flatter curve (kurtosis < 0)
A unitless measure of relative variation.
Coefficient of variation
What is the difference between discrete and continuous data?
Discrete phenomena have clear boundaries, such as roads, parcels, or categories like land cover classes.
Continuous phenomena vary gradually across space, like elevation or temperature.
What is the standard deviation of the following dataset:
4, 8, 6, 5, 2
Step1: Mean: (4+8+6+5+2)/5 = 5
Step2: Subtract the mean and square each difference EX: (8-5)2 = 9
Step3: Sum of Squares: (1+9+1+0+9 = 20)
Step4: Divide by n-1: n-1=5-1=4
Step5: Variance: 20/4 = 5
Step6: Take the square root: (5)1/2 = 2.24
The median center provides a potential location that minimizes _______
Total Euclidean Distance
a distribution of data with a narrower range and higher peak (kurtosis > 0)
Leptokurtic