A clinical trial accepts 2000 new patients each month. Half…

A clinical trial accepts 2000 new patients each month. Half of the patients are taking a placebo for 3 months. How many patients are taking the placebo on average at any given time? Hint: use Little’s Law: Inventory = Flow Rate * Flow time. Flow rate = number of patients per unit of time (month). How many patients each month? Note: among these patients, how many are taking the placebo? Flow time: how many months here?

Now, we want to see if we can design a process that operates…

Now, we want to see if we can design a process that operates with 5 employees instead of 7 (since there are 7 activities, some of the employees will perform more than 1 activity). We want to assign the activities in such a way that if an employee is in charge of more than one activity, these activities are adjacent (e.g., an employee can be assigned activities 1 and 2 but not 1 and 3). Moreover, realizing there might be setup costs involved with switching from one activity to another, we want to assign at most two activities to each employee.

Customer Support at Virtual Coach Virtual Coach is an on-lin…

Customer Support at Virtual Coach Virtual Coach is an on-line personal training service that allows athletes to upload their training data (heart-rate, watts, perceived exertion, speed, etc.) and then provides personalized training plans. To support the service, they operate a small call center that receives an average of 50 calls per hour. Of these 50 calls, 45 are STANDARD and 5 are NEW USER. STANDARD calls have to do with mainly login issues or minor technical questions and take 2 minutes to answer. NEW USER calls require an agent to walk the person through the use of the software, and they take 23 minutes to answer. The coefficient of variation of call inter-arrival time is equal to 1 for both the STANDARD and the NEW USER calls. Also, there is little variation among both STANDARD calls and among NEW USER calls: the st. deviation of the time required for an agent to speak with a STANDARD or a NEW USER caller is effectively 0. Virtual Coach estimates that it costs about $0.75 for every minute that a STANDARD caller has to wait. On the other hand, because a NEW USER may be more likely to quit using the service if they have to wait, they estimate that it costs about $1.5 for every minute that a NEW USER has to wait. Currently, Virtual Coach has two employees dedicated to serving calls from STANDARD callers and 3 employees dedicated to answering calls from NEW USERS.  Each type of call has its own queue.