Stress Response Uncertainty Worksheet Features 
After the measurement of a subject parameter has been made, the parameter may be subjected to stresses during shipment or transport to the using location. For example, this may occur when a parameter has been sent to an outside agency or lab for calibration or testing and is subsequently returned to the using organization. 

The impact of the shipping and handling stresses on the measurement uncertainty obtained by calibration or testing can be assessed by identifying each relevant stress and quantifying the associated stress response. UncertaintyAnalyzer assumes that uncertainties due to shipping and handling stresses are normally distributed unless the degrees of freedom are less than infinite or the % Confidence is 100%.  If the degrees of freedom are less than infinite and the % Confidence is less than 100%, the Student's t distribution is used. If the % Confidence is 100%, then the Uniform distribution is used and the degrees of freedom are assumed to be infinite. 

The Error Source Table of the Stress Response Uncertainty Worksheet provides for up to 30 stress response error sources in estimating the total uncertainty in the value of the subject parameter due to shipping and handling stress. 
Brief descriptions of the table headers are given below. 

Event Description
A description of the source of the stress response error is entered in the Event Description column. In the example of the subject parameter calibrated or tested by an outside agency, a suitable Event Description might be “Delivery to Customer.”

Stress Limits
The ± limits that bound stresses that may be encountered from a given source (e.g., vibration, heat, humidity, etc.) are entered in the Stress Limits column. Alternatively, the limit may be computed from entered Stress Uncertainty and % Confidence.

% Confidence
The probability that stresses will be contained within the stress limits is entered in the % Confidence box. Alternatively, the % Confidence may be computed from entered Stress Limits and Stress Uncertainty.

Stress Uncertainty
Stress Uncertainty is the uncertainty in the stress that the subject parameter has been exposed to during shipping and handling. The Stress Uncertainty is either computed from the Stress Limits and % Confidence, or can be entered directly.

Deg. Freedom (or Sample Size)
Selecting Degrees of Freedom (or Sample Size) on the menu opens the Type B Degrees of Freedom Calculator screen for computing the degrees of freedom for heuristically determined uncertainty estimates. 

Response Coefficient
The Response Coefficient relates stress response to stress level. It converts the level of stress, in whatever units it is expressed in (e.g., g's of acceleration, °C temperature, etc.) to the expected response, which is expressed in the subject parameter measurement uncertainty units (e.g., mV, cm, etc.). The Response Coefficient also relates the Response Uncertainty to the Stress Uncertainty.  Response coefficient values for given stress levels are typically obtained from experiments or from manufacturer specifications. The Response Coefficient is expressed in terms of the measurement uncertainty units divided by the stress units (e.g., mV / g). 

Response Uncertainty
The Response Uncertainty column displays the uncertainty in a measured subject parameter value due to a given stress response. The Response Uncertainty is the product of the Stress Uncertainty and the Response Coefficient. 
The Response Uncertainty is expressed in terms of the subject parameter tolerance units.

Total Stress Response Uncertainty

The bottom section of the Stress Response Uncertainty Worksheet displays the total uncertainty due to shipping and handling stress. The uncertainties resulting from the individual stress response errors are combined in root-sum-square (RSS).  The Degrees of Freedom for the Combined Uncertainty is computed using the Welch-Satterthwaite formula.