phosphor: Phosphorus Content Data

Description Usage Format Source Examples

Description

This dataset investigates the effect from inorganic and organic Phosphorus in the soil upon the phosphorus content of the corn grown in this soil, from Prescott (1975).

Usage

1

Format

A data frame with 18 observations on the following 3 variables.

inorg

Inorganic soil Phosphorus

organic

Organic soil Phosphorus

plant

Plant Phosphorus content

Source

P. J. Rousseeuw and A. M. Leroy (1987) Robust Regression and Outlier Detection. Wiley, p.156, table 24.

Examples

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data(phosphor)
plot(phosphor)
summary(lm.phosphor <- lm(plant ~ ., data = phosphor))
summary(lts.phosphor <- ltsReg(plant ~ ., data = phosphor))

phosphor.x <- data.matrix(phosphor[, 1:2])
cPh <- covMcd(phosphor.x)
plot(cPh, "dd")

Example output

Call:
lm(formula = plant ~ ., data = phosphor)

Residuals:
    Min      1Q  Median      3Q     Max 
-32.828  -8.440  -1.118   6.694  58.757 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)   
(Intercept) 56.25102   16.31074   3.449  0.00358 **
inorg        1.78977    0.55674   3.215  0.00579 **
organic      0.08665    0.41494   0.209  0.83740   
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 20.68 on 15 degrees of freedom
Multiple R-squared:  0.4823,	Adjusted R-squared:  0.4133 
F-statistic: 6.988 on 2 and 15 DF,  p-value: 0.00717


Call:
ltsReg.formula(formula = plant ~ ., data = phosphor)

Residuals (from reweighted LS):
     Min       1Q   Median       3Q      Max 
-30.2967  -3.5911  -0.6916   4.2514  17.1156 

Coefficients:
          Estimate Std. Error t value Pr(>|t|)    
Intercept 60.91489   10.19950   5.972 3.41e-05 ***
inorg      1.21103    0.35494   3.412  0.00421 ** 
organic    0.08833    0.25742   0.343  0.73661    
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 12.69 on 14 degrees of freedom
Multiple R-Squared: 0.5188,	Adjusted R-squared: 0.4501 
F-statistic: 7.548 on 2 and 14 DF,  p-value: 0.005972 

robustbase documentation built on Nov. 17, 2017, 6:46 a.m.