Flower

Description

A data set with the dry mass of all flowers and the dry mass of the total plant from 20 species growing at high and 20 species growing at low altitude.

Usage

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Format

A data frame with 40 observations on the following 3 variables.

alt

a factor with levels high low

flower

a numeric vector; dry mass of flowers in mg

total

a numeric vector; dry mass of total plant in mg

Details

The data sets shows a random subsample of the original data set.

Source

Fabbro, T. & Koerner, Ch. (2004): Altitudinal differences in flower traits and reproductive allocation. FLORA 199, 70-81. Fabbro, Koerner ()

Examples

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data(flowers)






## a model with two intercepts and two slopes
#  m1 <-lm(log(flower) ~ alt/log(total) -1, data=flowers)
#
## a model with two intercepts and one slope
#  altdiff <- rbind("high-low"=c(1,-1))
#  m2 <- lm(log(flower) ~ alt + log(total), data=flowers,
#           contrasts=list(alt=mycontr(contr=altdiff)))
#
## are separate slopes needed?
#  anova(m1, m2) # conclusion:
#
## no difference in slopes but difference in intercept
## for interpretation also test whether the slope is one!