Dear R-helpers,
I have a linear model with a year effect (year is coded as a factor), i.e.
the parameter estimates for each level of my year variable have significant
P values (see some output below) and I am interested in testing:
a) the overall effect of year;
b) the significance of each year vis-a-vis every other year (the model
output only tests each year against the baseline year).
I'd appreciate any help with how to perform these post-hoc tests in R.
Many thanks,
Mark Na
Call:
lm(formula = data$SR.obs ~ log(data$AREA, 10) + data$YEAR,
subset = (data$AREA >= 14.5))
Residuals:
Min 1Q Median 3Q Max
-5.3412 -1.3140 0.1108 1.1972 4.3126
Coefficients:
Estimate Std. Error t value Pr(>|t|)
(Intercept) -9.4606 0.6144 -15.399 < 2e-16 ***
log(data$AREA, 10) 3.9261 0.1734 22.644 < 2e-16 ***
data$YEAR2008 1.0750 0.2854 3.767 0.000211 ***
data$YEAR2009 1.5884 0.3073 5.169 5.18e-07 ***
---
Signif. codes: 0 *** 0.001 ** 0.01 * 0.05 . 0.1 1
Residual standard error: 1.822 on 226 degrees of freedom
Multiple R-squared: 0.6945, Adjusted R-squared: 0.6905
F-statistic: 171.3 on 3 and 226 DF, p-value: < 2.2e-16
[1] "AIC= 934.557"
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