Assignment 5 Purpose: comparison of models and reporting on the conclusions. Models supposed to be correct, so e.g. apparently increased keeper productivity for BF+ model w.r.t. current. Individual models were not uniformly tested. Time unit: hours for current and minutes for others. Make uniform, decide on simulation durations (crash of normal model), and assess confidence. Do not take simulation results for granted, try to explain!

Miscellanous exercises

A job can be executed either by resource R1 (alone) or by resources R2 and R3 in succession. What are the differences in resource handling between the following three conceptual models? How does it affect the performance? How would each be implemented e.g. in Arena? What parameters are needed for an implementation?

Give a choice-free equivalent to the following Arena model, by adding another create block. What are the parameters of the new model?

Choose the appriopriate construction for a simulation model. What are the parameters, how should they be determined? 1. An street ice cream vendor's order arrival process on a warm sunday. It is not constant throughout the day! 2. Processing income tax forms: a choice is made between a superficial or thorough check. The choice depends on a weighted random draw. The weight is based on properties of the form and the current resource capacity. 3. Processing time of a production step with measured average duration and stddev of respectively a. 7.2 minutes / 4.1 minutes, b hours / 0.38 hours, c minutes / 41.5 minutes.

The current situation C and two tentative improvements I 1,2 are assessed by simulation. Some trial runs show that I 1,2 are likely to reduce performance indicator x relative to C, but there is no clear "winner". Confidence from the trial runs of any improvement beating the current situation is less than 90%. Just before the deadline for writing the final report, long simu- lations are carried out for each model, with the following results: C I1I1 IndicatorAverageHalf Width x x I2I2 x How do you report your findings? What do you recommend?

We may safely assume that different simulation runs are independent (at worst). So we can tabulate the differences: C-I 1 Av HW Stdev=HW/1.96 A/S Conf(>0) C-I 2 Z | | | | | | | | | | | | | | | | | | | | | | Report: Both solutions seem to improve current situation (plm. 90% confidence). No clear winner. Implementation depends on costs I 2 -I 1