Stability Study - Options
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Stat > Regression > Stability Study > Stability Study > Options

Indicated whether batch is a fixed factor or a random factor. You can also change the confidence level and alpha for the analyses.

During model selection, Minitab evaluates first the batch by time interaction, and then the batch term. If the p-value for the term is greater than or equal to Alpha for pooling batches, then the term is removed from the model. Otherwise, the term remains in the model and model selection ends.

Dialog box items

No batch factor

50 percent (corresponds to mean response): Choose to calculate the shelf life based on the mean of the response values. Minitab calculates the percentiles based on the normal distribution, so the 50th percentile is equal to the mean.

Other percent: Choose to calculate the shelf life based on the percentile that you specify.

Confidence level: Enter the level of confidence for the confidence interval.

Batch is a fixed factor

Batch is a fixed factor: Choose if you did not randomly select the batches for your study. For more information, see Fixed versus random batch.

50 percent (corresponds to mean response): Choose to calculate the shelf life based on the mean of the response values. Minitab calculates the percentiles based on the normal distribution, so the 50th percentile is equal to the mean.

Other percent: Choose to calculate the shelf life based on the percentile that you specify.

Confidence level: Enter the level of confidence for the confidence interval.

Alpha for pooling batches: Specify the level of significance for model selection.

Batch is a random factor

Batch is a random factor: Choose if you randomly selected the batches for the study. For more information, see Fixed versus random batch.

Percent: Choose to calculate the shelf life based on the percentile that you specify.

Confidence level: Enter the level of confidence for the confidence interval.

Alpha for pooling batches: Specify the level of significance for model selection.

Provide starting estimates for variance components: Check to specify starting estimates. Otherwise, Minitab uses the minimum normal quadratic unbiased estimation (MINQUE) estimates. The MINQUE estimates are typically good estimates.

Batch: Specify a starting estimate for the variance component of the batch factor.

Batch x Time: Specify a starting estimate for the variance component of the batch by time interaction (Batch x Time).

Error: Specify a starting estimate for the variance component of the error variance.

Maximum number of iterations: Specify the maximum number of iterations for estimating the unknown parameters in the models.