Provide starting estimates for model parameters in a regression with life data model

Minitab uses a modified Newton-Raphson algorithm to estimate the model parameters. When Minitab estimates the parameters from the data, you can specify starting values for the algorithm and specify the maximum number of iterations.

In the worksheet, enter a column with entries that correspond to the model terms. Use the order that you will enter the terms in the Model field. With complicated models, you can determine the order of entries for the starting estimates column by running the analysis with the default starting estimates. The order of the estimates is the same as the order of the parameters in the regression table in the output.

The maximum likelihood solution may not converge if the starting estimates are far from the true solution. Therefore, you should enter approximate starting values for the parameter estimates.

  1. Choose Stat > Reliability/Survival > Regression with Life Data.
  2. Click Options.
  3. In Use starting estimates, enter the column of starting estimates for the algorithm.
  4. In Maximum number of iterations, enter the maximum number of iterations for reaching convergence (the default is 20).

    Minitab obtains maximum likelihood estimates through an iterative process. If the maximum number of iterations is obtained before convergence, the algorithm stops.

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