Enter your data for Probit Analysis

Stat > Reliability/Survival > Probit Analysis

Enter your data

Select the option that best describes your data.

Response in event/trial format

If your data indicate the number of events (failures) and the total number of trials at each stress level, complete the following steps.

  1. In Number of events, enter the column that contains the number of events (failures).
  2. In Number of trials, enter the column that contains the total number of items that were tested at each stress level.
  3. In Stress (stimulus), enter a column of stress or stimulus levels.
  4. If you want to include a factor, enter the column in Factor (optional). The factor is an additional categorical variable, such as a group classification, that may also affect the failure response (in addition to the stress or stimulus).
In this worksheet, the Temp column contains the stress levels. The Failures column contains the number of events, which is the number of items that failed at the stress level. The Trials column contains the total number of items tested at each stress level. For example, at a temperature of 140, 7 of 10 items failed (7 events).
C1 C2 C3
Temp Failures Trials
80 2 10
120 4 10
140 7 10
160 9 10

Response in response/frequency format

If your data indicate the number of items that failed and the number of items that survived at each stress level, complete the following steps.

  1. In Response, enter the column that indicates whether each item failed or survived.
  2. If you have counts for each response, in Frequency (optional), enter a column that indicates the number of items that failed and survived at each stress level.
  3. In Stress (stimulus), enter a column of stress or stimulus levels.
  4. If you want to include a factor, enter the column in Factor (optional). The factor is an additional categorical variable, such as a group classification, that may also affect the failure response (in addition to the stress or stimulus).
In this worksheet, the Temp column contains stress levels. The Response column contains values that indicate whether each item failed or not. The higher value corresponds to an event (the item failed). The Count column indicates how many times the specific response occurred. For example, at a temperature of 160, 9 units failed (9 events) and 1 unit did not fail (1 non-event).
C1 C2 C3
Temp Response Count
80 1 2
80 0 8
120 1 4
120 0 6
140 1 7
140 0 3
160 1 9
160 0 1

Assumed distribution

Select a distribution to model your data. Base your decision on process knowledge or use probability plots to evaluate the model fit. For more information, go to Distribution fit for reliability analysis.

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