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Before we start with simulation, we need to collect data.

 

First the difference between attibute data and variable data.

 

 

ATTRIBUTE                        VARIABLE

 

OK / NOK                               21,7° C

0 / 1                                     19 sec

Good / False                         2m 66cm

Minimum  sample 100           Minimum sample 30

 

 

From this analogy, one can see that variable data provides more information than attribute data. As input for our simulation projects we prefer to receive variable data.

  

 

VARIATION

 

Variation is our enemy, but a need for simulation accuracy. Still we should aim to  keep the variation for measurement as small as possible.

 

Known as the 5Ms and 1P, these sources of variation are common to all processes, whether manufacturing or business-based.

 

 

Machines – The equipment used in the transformation of inputs into outputs, e.g., a computer that turns various sources of information into an organized report.

 

Materials – The elements transformed from inputs to outputs, e.g., the paints and canvas used by a painter.

 

Methods – The procedures that transform inputs into outputs, e.g., a standard procedure for billing and collections.

 

Measurement – The tools that monitor a process’s performance, e.g., a doctor’s reading of a patient’s blood pressure.

 

Mother Nature – The environmental elements that influence the ability to meet a customer need or requirement, e.g., regulation of temperature and humidity in a paper warehouse.

 

People – The staffing that influences the ability to meet customer needs and requirements, e.g., the number of operators per shift

 

Variation in a process may be caused by any one of these factors or by the interaction of two or more, such as machines and materials.

 

 

SAMPLING

 

 

Populatie vs Sample

 

A population is the entire group of objects from which information is needed for a statistical study. A sample is the group of objects selected from the population from which data is gathered for a statistical study.

 

We can consider the relationship between the population and the sample in two ways:

 

 

Physically, the sample is a subset of the population.

Statistically, a properly selected sample should mirror the population.

 

 

Sample size should be small enough to be affordable, and large enough to accurate.

 

 

 

GOOD MEASUREMENT LEADS TO….

 

Accuracy – how close the indicated value is to the true value

 

Stability – ability to produce the same results over time

 

Linearity – difference in accuracy across the range of measures

 

Repeatability – variability in values when everything else is held constant

 

Reproducibility – variability in values with different people measuring elements under the same conditions

 

 

THINGS TO CHECK…

 

-          Is your data validated?

-          Is the method of measurement OK?

-          Is the data un-interpretable?

-          Only include data intended to use.

 

 

 

 

 

 

 

VALUABLE  INFORMATION FOR SIMULATION?

 

·          Lay-out

·          Products, demand

·          Routings

·          Timing : set-up, proces, MTBF, MTTR

·          Capacity

·          Controls en priority

·          Failures

·          Rework?? Hidden workflow??

 

You can only use input which is available and accurate.

Good to know is that a complexity level of 20 % already returns a model accuracy of 80 %.

 

Did you know that…

CAD files, JT files, JPEG’s, etc can be imported for more realistic and personalized simulations.