fit.sensitivity.plot: Visualise fit sensitivity for a breakage-resistance model
In breakage: SICM pipette tip geometry estimation

Description Usage Arguments Value Author(s) See Also Examples

Plots a contour map of the sensitivity of the residual error of a breakage resistance model to variation of the fitted parameters. This should give some idea of the goodness of the fit.

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fit.sensitivity.plot(data, fit, rho = 51, l = 1000,
    r.range = 0.015, theta.range = pi/360, steps = 100,
    nlevels = 200, r.squared = TRUE, bound.at = 0.99, ...)

`data`	Measured breakage data as an XY list or data frame, with `data$x` holding the breakage distances in microns, and `data$y` the corresponding resistance in megohms. For compatibility with `breakage.plot` and `break.clust`, these columns may instead by named `Z` and `Mohm` respectively.
`fit`	The fitting results list returned by `fit.breakage`
`rho`	Resistivity of the filler solution, in ohm centimetres. Must be the same value used for fitting or the plot will be incorrect.
`l`	The initial length of the pipette tip, in microns. Must be the same value used for fitting or the plot will be incorrect.
`r.range`	The range above and below the fitted inner radius result, `r`, to test and plot, in microns.
`theta.range`	The range above and below the fitted half-cone angle result, `theta`, to test and plot, in radians.
`steps`	The total number of steps to evaluate in both directions.
`nlevels`	The number of contour lines to draw.
`r.squared`	Whether to plot the error value directly, or transform it to plot the coefficient of determination (or R-squared) instead. The latter is plotted by default. It contains the same information in marginally more convenient form, but its use might be considered misleading if taken as implying a linear model.
`bound.at`	A level at which to plot a significance contour. This is on top of the `nlevels` contours automatically positioned by the main plot, and plotted in a different colour.
`...`	Any additional parameters to be passed to the main `contour` plot.

`x`	The x (theta) values of the plotted surface.
`y`	The y (radius) values of the plotted surface.
`z`	The z (error) values of the plotted surface.

Matthew Caldwell

fit.breakage,

# fake up some breakage data
brks <- sort(abs(0.5 + rnorm(n=15, sd=0.5) * 1:15))
res <- resist.breakage(brks, theta=3*pi/180, r=0.04, rho=64) + rnorm(15)
dat <- list(x=brks, y=res)

# fit it
fit <- fit.breakage(dat, do.plot=FALSE)

# plot the sensitivity surface
fit.sensitivity.plot(dat, fit)