Statistics help!?

Question

The table below records for each of 11 plots of barley a measure of the extent of mildew
attack (actually the percentage of third youngest leaf area affected) and the ultimate yield of
grain in units of t/ha.

mildew (x) yield (y)
0.7----------- 4.41
2.6----------- 4.26
2.6----------- 4.38
4.3----------- 3.90
4.8----------- 4.28
0.9----------- 4.60
mildew (x) yield (y)
6.5----------- 3.87
2.4----------- 4.04
4.1----------- 4.16
4.7----------- 3.93
0.8----------- 4.60

(a) Perform a linear regression analysis using R. Explain any inference you can make from
the results.
(b) Plot the data and the fitted line.
(c) Using the equation of the straight line, predict the yield when mildew = 1.5.
(d) Find the correlation between the two variables.

Answer 1

> mildew <- c(0.7, 2.6, 2.6, 4.3, 4.8, 0.9, 6.5, 2.4, 4.1, 4.7, 0.8)
> yield <- c(4.41, 4.26, 4.28, 3.90, 4.28, 4.60, 3.87, 4.04, 4.16, 3.93, 4.60)
> data <- matrix( c(mildew, yield), nrow = 11, ncol = 2, FALSE)
> regressionLine <- lm(yield ~ mildew)
> plot(mildew, yield)
> abline(regressionLine)

know you have the scatter plot and regression line

the regression line is: y = -0.1124 * x + 4.5634

if x = 1.5 then y = 4.3948

the correlation is found via:

> cor(data)

you'll find the correlation to be -0.8228063

Answer 2

I think you need to do the calculation yourself, then come back with more specific questions if necessary.