Cartographic Skills Lab II - Statistics

Amadeusz Zajac

GiS 3015: Cartographic Skills

Module 2 Lab

Polynomial Trendline

California:

Polynomial Trendline Equation:  y = 12.792x² - 50819x + 5E+07
R² = 0.9975

Florida:

Polynomial Trendline Equation: y = 0.2452x² - 767.37x + 569151
R² = 1

New York:

Polynomial Trendline Equation: y = 2.0052x² - 8003.3x + 8E+06
R² = 0.9978

Texas:

Polynomial Trendline Equation: y = 0.3388x² - 1080.7x + 826194
R² = 1

The polynomial patterns on this graph are great for showing not only the increase of the population in a given US state over time, but also to express the acceleration/deceleration of the change. The number of a given year can therefore be calculated according to the change in the increase, as opposed to according to the average of the few pieces of data we know.

As taken from the Module 2 lab:

California:

Estimated 2050 population using polynomial: 81963

Florida:

Estimated 2050 population using polynomial: 26495.5

New York:

Estimated 2050 population using polynomial: 44201.2

Texas:

Estimated 2050 population using polynomial: 34566

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-I Experienced a lot of difficulty converting some of the polynomial formulas into decipherable numbers but thanks to the classmates on discussion threads I managed to convert them by right-clicking on the formula, and going into “Format Trendline Label” and switching from “general” to “number”. This option would not work until the trendline was deleted and re-done, most likely because putting a label (such as "California") in one of the formula windows fooled the program into thinking the two were related.