RGA Glossary - Revision history

Lisa Hacker at 20:41, 18 September 2023

2023-09-18T20:41:29Z

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	{{template:RGA BOOK ~~SUB~~\|Appendix F\|Glossary}}		{{template:RGA BOOK\|Appendix F\|Glossary}}
	*'''"A" Mode:''' A failure mode for which a corrective action will not be implemented.		*'''"A" Mode:''' A failure mode for which a corrective action will not be implemented.

Chris Kahn at 21:28, 22 January 2014

2014-01-22T21:28:22Z

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	*'''Beta:''' The shape parameter for the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] and [[Crow Extended]] models. Beta must be greater than zero.		*'''Beta:''' The shape parameter for the [[Crow-AMSAA (NHPP)\|Crow-AMSAA (NHPP)]] and [[Crow Extended]] models. Beta must be greater than zero.


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	*'''Growth Rate:''' Represents the rate at which the MTBF of the system is increasing. The growth rate for the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] model is equal to <math>1 - \beta\,\!</math> and is therefore a value greater than or equal to zero,but less than 1. For the [[Duane Model]], the growth rate (<math>\alpha\,\!</math>) is the negative of the slope of the line on the cumulative failure intensity vs. time plot. A growth rate that is equal to 1 implies an infinite MTBF growth.		*'''Growth Rate:''' Represents the rate at which the MTBF of the system is increasing. The growth rate for the [[Crow-AMSAA (NHPP)\|Crow-AMSAA (NHPP)]] model is equal to <math>1 - \beta\,\!</math> and is therefore a value greater than or equal to zero,but less than 1. For the [[Duane Model]], the growth rate (<math>\alpha\,\!</math>) is the negative of the slope of the line on the cumulative failure intensity vs. time plot. A growth rate that is equal to 1 implies an infinite MTBF growth.


	*'''Homogeneous Poisson Process (HPP):''' A homogeneous process is equivalent to the widely used Poisson distribution. In this scenario, the system's failure intensity is not affected by age. Therefore, the expected number of failures associated with the system is accumulated at a constant rate. It is a special case of the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] model when <math>\beta = 1\,\!</math>.		*'''Homogeneous Poisson Process (HPP):''' A homogeneous process is equivalent to the widely used Poisson distribution. In this scenario, the system's failure intensity is not affected by age. Therefore, the expected number of failures associated with the system is accumulated at a constant rate. It is a special case of the [[Crow-AMSAA (NHPP)\|Crow-AMSAA (NHPP)]] model when <math>\beta = 1\,\!</math>.


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	*'''Lambda:''' The scale parameter for the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] and [[Crow Extended]] models. Lambda must be greater than zero.		*'''Lambda:''' The scale parameter for the [[Crow-AMSAA (NHPP)\|Crow-AMSAA (NHPP)]] and [[Crow Extended]] models. Lambda must be greater than zero.

David J. Groebel at 00:33, 17 January 2014

2014-01-17T00:33:17Z

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	*'''MIL-HDBK-189:''' Military handbook for reliability growth management. MIL-HDBK 189C can be downloaded by clicking [http://www.weibull.com/mil_std/mil_hdbk_189c.pdf here].		*'''MIL-HDBK-189:''' Military handbook for reliability growth management. MIL-HDBK-189C can be downloaded by clicking [http://www.weibull.com/mil_std/mil_hdbk_189c.pdf here].

David J. Groebel at 00:32, 17 January 2014

2014-01-17T00:32:40Z

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	*'''MIL-HDBK-189:''' Military handbook for reliability growth management.		*'''MIL-HDBK-189:''' Military handbook for reliability growth management. MIL-HDBK 189C can be downloaded by clicking [http://www.weibull.com/mil_std/mil_hdbk_189c.pdf here].

Kate Racaza at 15:53, 25 October 2012

2012-10-25T15:53:49Z

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	*Likelihood Value: The log-likelihood value returned by the likelihood function given the estimated parameters. This value is returned when maximum likelihood estimation (MLE) is used to estimate the parameters.		*'''Likelihood Value''': The log-likelihood value returned by the likelihood function given the estimated parameters. This value is returned when maximum likelihood estimation (MLE) is used to estimate the parameters.

Kate Racaza at 21:21, 4 October 2012

2012-10-04T21:21:33Z

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Lisa Hacker at 16:33, 26 September 2012

2012-09-26T16:33:52Z

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Kate Racaza at 17:07, 25 September 2012

2012-09-25T17:07:20Z

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	{{template:RGA BOOK\|F\|Glossary}}		{{template:RGA BOOK SUB\|Appendix F\|Glossary}}
	'''A Mode:''' A failure mode for which a corrective action will not be implemented.		'''A Mode:''' A failure mode for which a corrective action will not be implemented.

Richard House at 20:50, 12 September 2012

2012-09-12T20:50:50Z

Richard House at 22:40, 11 September 2012

2012-09-11T22:40:10Z

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	'''Discovery Rate Beta:''' Indicates if the interarrival times between unique BD modes are getting larger or smaller. In most cases, we want this value to be less than 1 assuming that most failures will be identified early on, and their inter-arrival times will become larger as the test progresses.		'''Discovery Rate Beta:''' Indicates if the interarrival times between unique BD modes are getting larger or smaller. In most cases, we want this value to be less than 1 assuming that most failures will be identified early on, and their inter-arrival times will become larger as the test progresses.

	'''Discovery Rate Failure Intensity:''' The failure intensity of the unseen BD modes. This is represented by h(t).		'''Discovery Rate Failure Intensity:''' The failure intensity of the unseen BD modes. This is represented by <math>h(t)\,\!</math>.

	'''Discovery Rate MTBF:''' The rate at which the next new unique BD mode will be observed. This is represented by the inverse of h(t).		'''Discovery Rate MTBF:''' The rate at which the next new unique BD mode will be observed. This is represented by the inverse of <math>h(t)\,\!</math>.

	'''Demonstrated/Achieved Failure Intensity:''' Instantaneous failure intensity at the termination time.		'''Demonstrated/Achieved Failure Intensity:''' Instantaneous failure intensity at the termination time.
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	'''Effectiveness Factor:''' Portion of the BD mode's failure intensity that is expected to be removed based on the planned corrective action. This applies only to delayed fixes.		'''Effectiveness Factor:''' Portion of the BD mode's failure intensity that is expected to be removed based on the planned corrective action. This applies only to delayed fixes.

	'''Failure Intensity:''' The probability of failure within the next Δt given that the system may or may not have failed.		'''Failure Intensity:''' The probability of failure within the next <math>\Delta(t)\,\!</math> given that the system may or may not have failed.

	'''Failure Intensity Modes Seen:''' The failure intensity for the failure modes that have been seen during the test. This is calculated by subtracting the failure intensity of the modes that have not been seen from the total system failure intensity.		'''Failure Intensity Modes Seen:''' The failure intensity for the failure modes that have been seen during the test. This is calculated by subtracting the failure intensity of the modes that have not been seen from the total system failure intensity.
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	'''Growth Potential MTBF:''' Maximum MTBF that can be attained with the current management strategy. The maximum MTBF will be attained when all unique BD modes have been observed and fixed.		'''Growth Potential MTBF:''' Maximum MTBF that can be attained with the current management strategy. The maximum MTBF will be attained when all unique BD modes have been observed and fixed.

	'''Growth Rate:''' Represents the rate at which the MTBF of the system is increasing. The growth rate for the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] model is equal to 1 - β and is therefore a value greater than or equal to zero and less than 1. For the [[Duane Model]], the growth rate (α) is the negative of the slope of the line on the cumulative failure intensity vs. time plot. Growth rate equal to 1 implies infinite MTBF growth.		'''Growth Rate:''' Represents the rate at which the MTBF of the system is increasing. The growth rate for the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] model is equal to <math>1 - \beta\,\!</math> and is therefore a value greater than or equal to zero and less than 1. For the [[Duane Model]], the growth rate (<math>\alpha\,\!</math>) is the negative of the slope of the line on the cumulative failure intensity vs. time plot. Growth rate equal to 1 implies infinite MTBF growth.

	'''Homogeneous Poisson Process (HPP):''' A homogeneous process is equivalent to the widely used Poisson distribution. In this scenario, the system's failure intensity is not affected by age. Therefore, the expected number of failures associated with the system is accumulated at constant rate. It is a special case of the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] model when β = 1.		'''Homogeneous Poisson Process (HPP):''' A homogeneous process is equivalent to the widely used Poisson distribution. In this scenario, the system's failure intensity is not affected by age. Therefore, the expected number of failures associated with the system is accumulated at constant rate. It is a special case of the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] model when <math>\beta = 1\,\!</math>.

	'''Initial Failure Intensity:''' The failure intensity inherent to the system prior to any testing.		'''Initial Failure Intensity:''' The failure intensity inherent to the system prior to any testing.
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	'''Non-Homogeneous Poisson Process (NHPP):''' The NHPP is generally used to model the reliability of a repairable system. An NHPP is an extension of the HPP process. The NHPP allows for the system failure intensity to change with system age. Therefore, the expected number of failures associated with the system is not accumulated at a constant rate.		'''Non-Homogeneous Poisson Process (NHPP):''' The NHPP is generally used to model the reliability of a repairable system. An NHPP is an extension of the HPP process. The NHPP allows for the system failure intensity to change with system age. Therefore, the expected number of failures associated with the system is not accumulated at a constant rate.

	'''p ratio:''' The probability of not incorporating a corrective action by time T.		'''p ratio:''' The probability of not incorporating a corrective action by time <math>T\,\!</math>.

	'''Planned Growth:''' MTBF or failure intensity specified during a phase for the [[Crow Extended]] model for reliability growth planning.		'''Planned Growth:''' MTBF or failure intensity specified during a phase for the [[Crow Extended]] model for reliability growth planning.

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	'''Actual Growth Potential Factor:''' The failure intensity of the M modes (total number of distinct unfixed BD modes) after corrective actions have been implemented for them, using the actual values for the effectiveness factors. Used in the [[Crow Extended - Continuous Evaluation]] model.		'''Actual Growth Potential Factor:''' The failure intensity of the M modes (total number of distinct unfixed BD modes) after corrective actions have been implemented for them, using the actual values for the effectiveness factors. Used in the [[Crow Extended - Continuous Evaluation]] model.

	'''Actual Growth Potential Failure Intensity:''' The minimum attainable failure intensity based on the current management strategy. Used in the Crow Extended-Continuous Evaluation model.		'''Actual Growth Potential Failure Intensity:''' The minimum attainable failure intensity based on the current management strategy. Used in the [[Crow Extended - Continuous Evaluation]] model.

	'''Actual Growth Potential MTBF:''' The maximum attainable MTBF based on the current management strategy. Used in the Crow Extended-Continuous Evaluation model.		'''Actual Growth Potential MTBF:''' The maximum attainable MTBF based on the current management strategy. Used in the [[Crow Extended - Continuous Evaluation]] model.

	'''Actual Idealized Growth Curve:''' The reliability growth planning curve for the Crow Extended model that takes into account the fix delay.		'''Actual Idealized Growth Curve:''' The reliability growth planning curve for the [[Crow Extended]] model that takes into account the fix delay.

	'''Actual Projected Failure Intensity:''' The projected failure intensity based on the current management strategy. Used in the Crow Extended-Continuous Evaluation model.		'''Actual Projected Failure Intensity:''' The projected failure intensity based on the current management strategy. Used in the [[Crow Extended - Continuous Evaluation]] model.

	'''Actual Projected MTBF:''' The projected MTBF based on the current management strategy.		'''Actual Projected MTBF:''' The projected MTBF based on the current management strategy.
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	'''AMSAA:''' Army Materiel Systems Analysis Activity.		'''AMSAA:''' Army Materiel Systems Analysis Activity.

	'''Average Actual EF:''' An average of the effectiveness factors (EF) for the BD modes taking into account when the corrective action will be implemented. If the fix is going to be implemented at a later time or during another phase, then the EF value for the mode at the current analysis point is set to zero. If the delayed fix is going to be implemented at the current analysis point, then the EF value is set to the specified value for the mode. Used in the Crow Extended-Continuous Evaluation model.		'''Average Actual EF:''' An average of the effectiveness factors (EF) for the BD modes taking into account when the corrective action will be implemented. If the fix is going to be implemented at a later time or during another phase, then the EF value for the mode at the current analysis point is set to zero. If the delayed fix is going to be implemented at the current analysis point, then the EF value is set to the specified value for the mode. Used in the [[Crow Extended - Continuous Evaluation]] model.

	'''Average Fix Delay:''' The average test time required to incorporate corrective actions into the configuration. A fix delay can be specified for each phase of the reliability growth planning.		'''Average Fix Delay:''' The average test time required to incorporate corrective actions into the configuration. A fix delay can be specified for each phase of the reliability growth planning.
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	'''Average Nominal EF:''' An average of the effectiveness factors (EF) for the BD modes assuming all fixes for the seen BD modes will be implemented.		'''Average Nominal EF:''' An average of the effectiveness factors (EF) for the BD modes assuming all fixes for the seen BD modes will be implemented.

	'''BC Mode:''' For the Crow Extended model, a failure mode for which a corrective action will be implemented during the test. For the Crow Extended-Continuous Evaluation model, a failure mode for which a corrective action will be implemented at the time of failure.		'''BC Mode:''' For the [[Crow Extended]] model, a failure mode for which a corrective action will be implemented during the test. For the [[Crow Extended - Continuous Evaluation]] model, a failure mode for which a corrective action will be implemented at the time of failure.

	'''BD Mode:''' For the Crow Extended model, a failure mode for which a corrective action will be delayed until the end of the test. For the Crow Extended-Continuous Evaluation model, a failure mode for which a corrective action will be implemented at some point in time after the failure time.		'''BD Mode:''' For the [[Crow Extended]] model, a failure mode for which a corrective action will be delayed until the end of the test. For the [[Crow Extended - Continuous Evaluation]] model, a failure mode for which a corrective action will be implemented at some point in time after the failure time.

	'''BD Mode Failure Intensity:''' See Discovery Rate Failure Intensity.		'''BD Mode Failure Intensity:''' See Discovery Rate Failure Intensity.

	'''Beta:''' Shape parameter for the Crow-AMSAA (NHPP) and Crow Extended models. Beta must be greater than zero.		'''Beta:''' Shape parameter for the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] and [[Crow Extended]] models. Beta must be greater than zero.

	'''Chi-Squared GOF Test:''' A goodness-of-fit test that tests the hypothesis that the data follows a non-homogenous Poisson process (NHPP). This goodness-of-fit test is used in grouped data types.		'''Chi-Squared GOF Test:''' A goodness-of-fit test that tests the hypothesis that the data follows a non-homogenous Poisson process (NHPP). This goodness-of-fit test is used in grouped data types.
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	'''Growth Potential MTBF:''' Maximum MTBF that can be attained with the current management strategy. The maximum MTBF will be attained when all unique BD modes have been observed and fixed.		'''Growth Potential MTBF:''' Maximum MTBF that can be attained with the current management strategy. The maximum MTBF will be attained when all unique BD modes have been observed and fixed.

	'''Growth Rate:''' Represents the rate at which the MTBF of the system is increasing. The growth rate for the Crow-AMSAA (NHPP) model is equal to 1 - β and is therefore a value greater than or equal to zero and less than 1. For the Duane ~~model~~, the growth rate (α) is the negative of the slope of the line on the cumulative failure intensity vs. time plot. Growth rate equal to 1 implies infinite MTBF growth.		'''Growth Rate:''' Represents the rate at which the MTBF of the system is increasing. The growth rate for the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] model is equal to 1 - β and is therefore a value greater than or equal to zero and less than 1. For the [[Duane Model]], the growth rate (α) is the negative of the slope of the line on the cumulative failure intensity vs. time plot. Growth rate equal to 1 implies infinite MTBF growth.

	'''Homogeneous Poisson Process (HPP):''' A homogeneous process is equivalent to the widely used Poisson distribution. In this scenario, the system's failure intensity is not affected by age. Therefore, the expected number of failures associated with the system is accumulated at constant rate. It is a special case of the Crow-AMSAA (NHPP) model when β = 1.		'''Homogeneous Poisson Process (HPP):''' A homogeneous process is equivalent to the widely used Poisson distribution. In this scenario, the system's failure intensity is not affected by age. Therefore, the expected number of failures associated with the system is accumulated at constant rate. It is a special case of the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] model when β = 1.

	'''Initial Failure Intensity:''' The failure intensity inherent to the system prior to any testing.		'''Initial Failure Intensity:''' The failure intensity inherent to the system prior to any testing.
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	'''Integrated Reliability Growth Testing (IRGT):''' A process where reliability growth testing is conducted as part of existing testing procedures. This is less expensive that conducting a formal reliability growth test. IRGT is usually implemented at the same time as the basic reliability tasks. The test conditions under IRGT are usually less than actual customer use conditions.		'''Integrated Reliability Growth Testing (IRGT):''' A process where reliability growth testing is conducted as part of existing testing procedures. This is less expensive that conducting a formal reliability growth test. IRGT is usually implemented at the same time as the basic reliability tasks. The test conditions under IRGT are usually less than actual customer use conditions.

	'''Lambda:''' Scale parameter for the Crow-AMSAA (NHPP) and Crow Extended models. Lambda must be greater than zero.		'''Lambda:''' Scale parameter for the [[Crow-AMSAA - NHPP\|Crow-AMSAA (NHPP)]] and [[Crow Extended]] models. Lambda must be greater than zero.

	'''Laplace Trend Test:''' Tests the hypothesis that a trend does not exist within the data. The Laplace Trend Test can determine if the system is deteriorating, improving or if a trend does not exist.		'''Laplace Trend Test:''' Tests the hypothesis that a trend does not exist within the data. The Laplace Trend Test can determine if the system is deteriorating, improving or if a trend does not exist.
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	'''MTBF Modes Seen:''' The inverse of the failure intensity for the modes that have been seen during the test. See Failure Intensity Modes Seen.		'''MTBF Modes Seen:''' The inverse of the failure intensity for the modes that have been seen during the test. See Failure Intensity Modes Seen.

	'''Nominal Growth Potential Factor:''' The failure intensity of the M modes (total number of distinct unfixed BD modes) after corrective actions have been implemented for them, using the nominal values for the effectiveness factors. Used in the Crow Extended-Continuous Evaluation model.		'''Nominal Growth Potential Factor:''' The failure intensity of the M modes (total number of distinct unfixed BD modes) after corrective actions have been implemented for them, using the nominal values for the effectiveness factors. Used in the [[Crow Extended - Continuous Evaluation]] model.

	'''Nominal Growth Potential Failure Intensity:''' The minimum attainable failure intensity if all delayed corrective actions are implemented for the modes that have been seen and delayed corrective actions are also implemented for the unseen BD modes, assuming testing would continue until all unseen BD modes are revealed. Used in the Crow Extended-Continuous Evaluation model.		'''Nominal Growth Potential Failure Intensity:''' The minimum attainable failure intensity if all delayed corrective actions are implemented for the modes that have been seen and delayed corrective actions are also implemented for the unseen BD modes, assuming testing would continue until all unseen BD modes are revealed. Used in the [[Crow Extended - Continuous Evaluation]] model.

	'''Nominal Growth Potential MTBF:''' The maximum attainable MTBF if all delayed corrective actions are implemented for the modes that have been seen, and delayed corrective actions are also implemented for the unseen BD modes, assuming testing would continue until all unseen BD modes are revealed. Used in the Crow Extended-Continuous Evaluation ~~model~~.		'''Nominal Growth Potential MTBF:''' The maximum attainable MTBF if all delayed corrective actions are implemented for the modes that have been seen, and delayed corrective actions are also implemented for the unseen BD modes, assuming testing would continue until all unseen BD modes are revealed. Used in the [[Crow Extended - Continuous Evaluation]].

	'''Nominal Idealized Growth Curve:''' The reliability growth planning curve for the Crow Extended model that does not take into account the fix delay. The nominal curve assumes that all fixes are implemented instantaneously. Reliability growth is realized instantaneously on this curve since there is not a delay associated with the implemented fixes.		'''Nominal Idealized Growth Curve:''' The reliability growth planning curve for the [[Crow Extended]] model that does not take into account the fix delay. The nominal curve assumes that all fixes are implemented instantaneously. Reliability growth is realized instantaneously on this curve since there is not a delay associated with the implemented fixes.

	'''Nominal Projected Failure Intensity:''' The projected failure intensity assuming all delayed fixes for the modes that have been seen are implemented.		'''Nominal Projected Failure Intensity:''' The projected failure intensity assuming all delayed fixes for the modes that have been seen are implemented.

	'''Nominal Projected MTBF:''' The projected MTBF assuming all delayed fixes for the modes that have been seen are implemented. Used in the Crow Extended-Continuous Evaluation model.		'''Nominal Projected MTBF:''' The projected MTBF assuming all delayed fixes for the modes that have been seen are implemented. Used in the [[Crow Extended - Continuous Evaluation]] model.

	'''Non-Homogeneous Poisson Process (NHPP):''' The NHPP is generally used to model the reliability of a repairable system. An NHPP is an extension of the HPP process. The NHPP allows for the system failure intensity to change with system age. Therefore, the expected number of failures associated with the system is not accumulated at a constant rate.		'''Non-Homogeneous Poisson Process (NHPP):''' The NHPP is generally used to model the reliability of a repairable system. An NHPP is an extension of the HPP process. The NHPP allows for the system failure intensity to change with system age. Therefore, the expected number of failures associated with the system is not accumulated at a constant rate.
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	'''p ratio:''' The probability of not incorporating a corrective action by time T.		'''p ratio:''' The probability of not incorporating a corrective action by time T.

	'''Planned Growth:''' MTBF or failure intensity specified during a phase for the Crow Extended model for reliability growth planning.		'''Planned Growth:''' MTBF or failure intensity specified during a phase for the [[Crow Extended]] model for reliability growth planning.

	'''Projected Failure Intensity:''' The estimated failure intensity to be reached if the proposed delayed corrective actions are implemented, with the specified effectiveness factors. Used in the Crow Extended model.		'''Projected Failure Intensity:''' The estimated failure intensity to be reached if the proposed delayed corrective actions are implemented, with the specified effectiveness factors. Used in the [[Crow Extended]] model.

	'''Projected MTBF:''' The estimated MTBF to be reached if the proposed delayed corrective actions are implemented with the specified effectiveness factors. Used in the Crow Extended model.		'''Projected MTBF:''' The estimated MTBF to be reached if the proposed delayed corrective actions are implemented with the specified effectiveness factors. Used in the [[Crow Extended]] model.

	'''Reliability Growth:''' The positive improvement in a parameter or metric over a period of time due to changes in the system's design or manufacturing process.		'''Reliability Growth:''' The positive improvement in a parameter or metric over a period of time due to changes in the system's design or manufacturing process.