Launch the Fit Life by X Platform

Launch the Fit Life by X platform by selecting Analyze > Reliability and Survival > Fit Life by X.

The Fit Life by X launch window contains the following options:

Identifies the time to event (such as the time to failure) or time to censoring. With interval censoring, specify two Y variables, where one Y variable gives the lower limit and the other Y variable gives the upper limit for each unit. For details about censoring, see the Life Distribution chapter in this guide.

Identifies the accelerating factor.

Censor

Identifies censored observations. By default, 1 indicates a censored observation and 0 indicates an uncensored observation in your data table.

Freq

Identifies frequencies or observation counts when there are multiple units. If the value is 0 or a positive integer, then the value represents the frequencies or counts of observations for each row when there are multiple units recorded.

Identifies a column that creates a report consisting of separate analyses for each level of the variable.

Censor Code

After selecting the Censor column, select the value from the list that designates censoring. Missing values are excluded from the analysis. JMP attempts to detect the censor code and display it in the list.

Relationship

Determines the relationships between the event and the accelerating factor. Examples include transformation using the following acceleration models:

‒	Arrhenius Celsius: μ = b0 + b1 * 11605 / (X+273.15)

‒	Arrhenius Fahrenheit: μ = b0 + b1 * 11605 / ((X + 459.67)/1.8)

‒	Arrhenius Kelvin: μ = b0 + b1 * 11605/X

‒	Voltage: μ = b0 + b1 * log (X)

‒	Linear: μ=b0 + b1* X

‒	Log: μ = b0 + b1 * log(X)

‒	Logit: μ = b0 + b1 * log(x/(1-x))

‒	Reciprocal: μ = b0 + b1/X

‒	Square Root: μ = b0 + b1 * sqrt(x)

‒	Box-Cox: μ = b0 + b1 * Boxcox(X)

‒	Location: means μ is different for every level of X.

‒	Location and Scale: means μ and σ are both different for every level of X (equivalent to a Life Distribution fit with X as a By variable).

If you select Location or Location and Scale, a message might appear stating that “Analysis must exclude groups that are all right censored to continue Nested Model Tests. Do you want to continue?” Click Yes to continue the analysis. Right censored groups indicate groups where all observations are right censored. The message does not appear if your sample data does not include right censored observations.

See Custom Relationship if you want to use a Custom relationship for your model.

Nested Model Tests

Appends a nonparametric overlay plot, nested model tests, and a multiple probability plot to the report window.

Baseline

Enables you to enter a baseline value for the explanatory variable, X, of the acceleration factor. You can also set the baseline after launching the platform using the Set Time Acceleration Baseline option from the Fit Life by X red triangle menu.

Distribution

Specifies one distribution (Weibull, Lognormal, Loglogistic, Fréchet, SEV, Normal, Logistic, LEV, or Exponential distributions) at a time. Lognormal is the default setting.

Select Confidence Interval Method

Displays the method for computing confidence intervals for the parameters. The default is Wald, but you can select Likelihood instead. The Wald method is an approximation and runs faster. The Likelihood method provides more precise parameters but takes longer to compute.