{"id":16389,"date":"2016-11-16T06:21:31","date_gmt":"2016-11-16T06:21:31","guid":{"rendered":"http:\/\/www.safetyangel.com\/recdev\/?page_id=16389"},"modified":"2016-11-16T06:45:40","modified_gmt":"2016-11-16T06:45:40","slug":"example-ra-1-analyze-the-risk-of-allergic-reaction-to-suntan-lotion","status":"publish","type":"page","link":"http:\/\/www.safetyangel.com\/recdev\/example-ra-1-analyze-the-risk-of-allergic-reaction-to-suntan-lotion\/","title":{"rendered":"Example RA-1 – Analyze the Risk of Allergic Reaction to Suntan Lotion"},"content":{"rendered":"
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Example RA-1 - Analyze the Risk of Allergic Reaction to Suntan Lotion<\/h2><\/div><\/div><\/div><\/div><\/div>
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Examples provided here are purely for illustrating software features and functionality.<\/span><\/h3>\n<\/div><\/div><\/div><\/div><\/div><\/div><\/div>
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Example RA-1 – Analyze the Risk of Allergic Reaction to Suntan Lotion<\/span><\/h3>\n

Download Example File for Version 10 (*.rsgz10)<\/a> or Version 9 (*.rsr9)<\/a><\/b><\/p>\n

Problem Statement:<\/span><\/h3>\n

Assume that chemical X is added to a suntan lotion. The manufacturing process contains some minor variability. The concentration of chemical X is normally distributed with a mean of 0.005 and a standard deviation of 0.0001 ml of chemical X per ml of lotion.<\/p>\n

The amount of lotion applied by a person also varies and is known to be normally distributed with a mean of 100 ml and standard deviation of 20 ml.<\/p>\n

It is suspected that 10% of the population may, depending on the amount used, have an allergic reaction to chemical X. From the 10% who are susceptible, the probability that someone will have an allergic reaction is a function of the amount of the chemical applied. This probability is given by a Weibull distribution with beta of 2.5 and eta of 1.8.<\/p>\n

Determine the percentage of the population that is expected to experience an allergic reaction.<\/p>\n<\/div>

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Define the Resources<\/span><\/h3>\n

Define models to describe the concentration of chemical X in the suntan lotion and the amount of lotion applied, as shown below.<\/p>\n<\/div>

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Note that even though the amount of product is measured in milliliters, the Model Unit<\/b> has been set to Hours. This is because RENO flowchart results are always given in terms of the system base unit (SBU), and resources that require you to define a unit (i.e., Synthesis models) will have their values automatically converted to base units during simulation. Therefore, whenever you don’t want RENO to convert the value obtained from a model resource, simply make sure the model uses a unit that is defined as equal to 1 SBU. See the application help file<\/a> for more information.<\/p>\n

For this example, whenever one of the models returns a value as “X hours,” it should be read as “X ml.” If the model unit you are using is not equal to 1 SBU (choose File > Manage Repository > Manage Units<\/b> to confirm), you will need to change the model units before resimulating the flowchart.<\/p>\n

Define RENO static functions to calculate the amount of chemical X applied by the user and the likelihood that the user will have a reaction to the chemical.<\/p>\n<\/div><\/div>

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Here, Chemical_Applied is equal to the amount of lotion applied multiplied by the concentration of chemical X in the lotion. The equation uses the RENO internal function called “rvm” to return a random value based on the Application_ml model and the Concentration_ml model.<\/p>\n

Probability_Reaction uses the predefined function called “pr_weibull” to obtain a probability value based on the amount of chemical X applied. The function returns the probability from the Weibull cumulative distribution function evaluated at x. Here, the x value is based on the result of the Chemical_Applied function, and the parameters of the Weibull distribution are 2.5 (beta), 1.8 (eta) and 0 (gamma).<\/p>\n<\/div><\/div>

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Build the Flowchart<\/span><\/h3>\n

Construct the flowchart as follows:<\/p>\n<\/div>

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Step 1<\/b>: Use a standard block to calculate the percentage of the population affected, based on the probability of a reaction. This is calculated by multiplying the value of the probability by the percentage of the population that is susceptible (0.1), and then by 100 to convert the figure into a percentage.<\/p>\n

Step 2<\/b>: Use a result storage block to store the average of the results.<\/p>\n

Simulation<\/span><\/h3>\n

Run 2,000 simulations, with a seed of 1 for repeatability. The result shows that 0.424469% of the population is expected to experience a reaction to the lotion.<\/p>\n<\/div><\/div>

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