Fish & Wildlife Assessment

Trends Analysis
 

Theil Mehod is used to determine statistically significant trends of visibility and major aerosol chemical components in IMPROVE sites with long-term (e.g. > ~10 years) monitoring data.

An excel macro is developed to do the trend analysis. To run the trend analysis macro, right click the link and choose "Save Target As..." to save the excel file in your computer; Enter any time series of the data in sheet1 of the excel file as shown in the example; Push the "Trend Analysis" button on the bottom left of sheet1. The analysis will be done and the results, including the slope, S-Value and P-Value, will be outputted to sheet1.

The slope (units/year) indicates the overall trend of the time series of the data (positive indicates increase and negative indicates decrease). The cumulative probabilities (P-Value) are calculated based on the S-Value and the Kendall's Tau statistics, and used as significance criterion for trend evaluation. In EPA 1997 National Air Quality Trends Report, a 5% P-Value has been chosen as the significance criterion (if P-Value < 5%, the trend is considered statistically significant).

Fish and Wildlife Sites Trends Analysis Pages:

	Breton Island (IMPROVE sampling started in 2000, no trends analysis)
	Brigantine
	Cape Romain
	Chassahowitzka
	Mingo (IMPROVE sampling started in 2000, no trends analysis)
	Moosehorn
	Okefenokee
	Seney (IMPROVE sampling started in 2000, no trends analysis)
	St. Marks (IMPROVE sampling started in 2000, no trends analysis)
	Swanquarter (IMPROVE sampling started in 2000, no trends analysis)
	Wichita Mountains (IMPROVE sampling started in 2001, no trends analysis)
	Wolf Island (no IMPROVE site) is represented by Okefenokee