Quantile Regression: Salmonid Abundance vs. Metals Toxicity Units for Colorado Streams
- Analysis: Quantile regression
- Independent variable: Metal Toxicity Units
- Dependent variable: Number of Salmonids
- Key: dot=observation; line= 90th quantile
- Sample size: n = 30
- Number of Salmonids = 153.3 - 111.364*(Metal Toxicity Units)
- Date: 12 November, 2006
|Variable||Estimate||lower CL||upper CL||Test Type||Statistic||p|
|Metal Toxicity Units||-111.364||-656.511||433.782||T value||-0.418||0.679|
- Model generated using SAS Proc QUANTREG with the smoothing algorithm. The WALD and Likelihood test statistics were used to test the linear null hypothesis, H0: slope=0.
- Analysis for sites classified as pH neutral, but with strong AMD input.
- Metal Toxicity Units (TU) were calculated as sum of the ratios of each measured metal concentration with the criterion for that metal.
- Replicate visits to a site were not excluded from the data set.
- Agency: U.S. Environmental Protection Agency
- Program: Environmental Monitoring and Assessment Program (EMAP)
- Project: Colorado Metals Belt Stream Assessment (EPA Region 8)
- Filenames: Files benmet, fishmet and chem downloaded from the Surface Waters Information Management (S.W.I.M.S.) database web site.
- Data collected 1994 through 1995.
- Analyzed metals and metalloids: aluminum, arsenic, cadmium, chromium, copper, iron, manganese, nickel, lead, selenium, silver, zinc.
- A description of the sampling methods may be found in the EMAP West Methods Manual for Streams found on the S.W.I.M.S. database web site.
Patricia Shaw-Allen, email@example.com, (513) 569-7136