Factorial Reliability Designs: Analysis Results

The following information is provided in the analysis results for factorial reliability designs.

Analysis Results

The following table provides general information about the effects of the factors and factorial interactions on the times to failure. This information may be presented for individual factors and interactions or for groups of factors and interactions, depending on your analysis setting on the control panel.

This table includes the following columns:

- Model displays the model for which the results apply.
- - Reduced assumes that the product life is the same at different levels of each factor or interaction.
  - Full assumes that the product life is different at different levels of each factor or interaction.
- Effect is the factor or factorial interaction that caused the difference in the observed times-to-failure. If you have selected to use grouped terms in the analysis (specified on the Analysis Settings page of the control panel), the effects will be grouped by order (i.e., main effects, two-way interactions, etc.). Effects displayed in red are considered to be significant.
- Degrees of Freedom is the degrees of freedom of this source of variation. This is also the number of parameters in the model for this source.
- Ln(Likelihood Value) is the logarithm transformation of the likelihood value for this source of variation.
- Likelihood Ratio is the likelihood ratio value for this source of variation.
- P Value is the probability that LR is from a chi-squared distribution, which would indicate that the factor or factorial interaction has no effect on product life. This value is compared to the risk level (alpha) that you specify on the Analysis Settings page of the control panel. If the p value is less than alpha, then the factor or interaction is considered to have a significant effect on product life. In this case, the effect and its p value will be displayed in red.

The following table provides specific information on the contribution of each factor or factorial interaction to the variation in the times to failure and an analysis of the significance of this contribution.

This table includes the following columns:

- Term is the factor, factorial interaction, etc. under consideration. Terms displayed in red are considered to be significant.

Effect is a measure of how much the response value (Y) changes when the value of the corresponding term in the model changes from the low level to the high level.

- Coefficient is the regression coefficient of the term, which represents the contribution of the term to the variation in the response.
- Standard Error is the standard deviation of the regression coefficient.
- Low Confidence and High Confidence are the confidence bounds on the regression coefficient, using Fisher bounds.
- Z Value is the normalized regression coefficient, which is equal to Coefficient/Standard Error.
- P Value is the probability that an equal amount of variation in the output would be observed in the case that this source does not affect the output. This value is compared to the risk level (alpha) that you specify on the Analysis Settings page of the control panel. If the p value is less than alpha, this source of variation is considered to have a significant effect on the output. In this case, the term and its p value will be displayed in red.

Additional Results

All of the following tables provide information that was generated from the main calculations. The available tables will vary depending on the design type you are working with. The results that could be available include:

Alias Structure

Alias Summary

Var/Cov Matrix

Diagnostic Information

Least Squares Means

	Related Topics and Links:
	Analysis Summary Window