The Nelson
data frame has 128 rows and 3 columns of data from an
accelerated test of dialectric breakdown.
This data frame contains the following columns:
A numeric vector of dialectric breakdown strength values.
A numeric vector of time values.
A numeric vector of temperature values.
These data are the result of a study involving the analysis of performance degradation data from accelerated tests, published in IEEE Transactions on Reliability. The response variable is dialectric breakdown strength in kilovolts, and the predictor variables are time in weeks and temperature in degrees Celsius.
Nelson, W. (1981). Analysis of PerformanceDegradation Data. IEEE Transactions on Reliability. Vol. 2, R30, No. 2, pp. 149155.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23  Try < function(expr) if (!inherits(val < try(expr), "tryerror")) val
plot(y ~ x1, data = Nelson, log = "y")
plot(y ~ x2, data = Nelson, log = "y")
coplot(y ~ x1  x2, data = Nelson)
coplot(y ~ x2  x1, data = Nelson)
Try(fm1 < nls(log(y) ~ b1  b2*x1 * exp(b3*x2), data = Nelson,
start = c(b1 = 2, b2 = 0.0001, b3 = 0.01), trace = TRUE))
Try(fm1a < nls(log(y) ~ b1  b2*x1 * exp(b3*x2), data = Nelson,
trace = TRUE, alg = "port",
start = c(b1 = 2, b2 = 0.0001, b3 = 0.01)))
Try(fm2 < nls(log(y) ~ b1  b2*x1 * exp(b3*x2), data = Nelson,
start = c(b1 = 2.5, b2 = 0.000000005, b3 = 0.05), trace = TRUE))
Try(fm2 < nls(log(y) ~ b1  b2*x1 * exp(b3*x2), data = Nelson,
trace = TRUE, alg = "port",
start = c(b1 = 2.5, b2 = 0.000000005, b3 = 0.05)))
Try(fm3 < nls(log(y) ~ cbind(1, x1 * exp(b3*x2)), data = Nelson,
start = c(b3 = 0.01), trace = TRUE, algorithm = "plinear"))
Try(fm4 < nls(log(y) ~ cbind(1, x1 * exp(b3*x2)), data = Nelson,
start = c(b3 = 0.05), trace = TRUE, algorithm = "plinear"))

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