Statistical Process Improvement
Georgetown University

Causal Control Chart


Assigned Reading


  • Guide to constructing causal control charts Slides►


Instruction for Submission of Assignments: Assignments should be submitted directly on Blackboard.  In rare situations assignments can be sent directly by email to the instructor. Submission should follow these rules:

  1.  Submit only one document, usually an Excel file.  All questions should be answered in different sheets.  Each sheet should be labeled with the question number. 
  2. All Excel cells, except the cells containing the data, must have formulas.  Do not paste the value into the cell, it must be calculated using a formula.  Even simple steps, such as adding two numbers, should be done using formulas. 
  3. Make sure that any control charts follow the visual rules below:  (1) Control limits must be in red and without markers, (2) Observed lines must have markers, (3) X and Y axis must be labeled, and (4) Charts must be linked to the data. 
  4. Copy and paste SQL or R code into Excel sheet.  Plot data in Excel. 
  5. The first sheet in the file should be a summary page.  In the summary page you should list how your answers to the question differs from answers provided within the assignment (inside Teach One or other answers).  You must indicate for each question if your control chart is exactly the same as seen in Teach One or other formats.  For each question, you must indicate if the answers you have provided is the same as the answers supplied on the web.  If there are no answers provided, you must indicate that there were no answers available on the web to compare your answers to.

Question 1: There are many reasons for excessive boarding times in emergency rooms.  The following data shows the simulated experience of a hospital.  For each time period, we show the number of excessive boarding and total patients examined.  These numbers are divided into 4 strata each corresponding to presence of alternative reasons for backup; in particular whether there was image or hospital-bed back up present.  The pre-intervention period corresponds to before hiring additional personnel for the emergency room.  The post intervention refers to the period after hiring,  Create a control chart to examine if the addition of new personnel in the emergency room has led to decline of excessive boarding times. Data►

Question 2:  Estimate the effect of election of president Trump on healthcare stock of Humana Inc.  Election of president Trump was a surprise to many.  After his election, stock prices may reflect both his election as well as the stock's historical patterns. President Trump had promised to repeal and perhaps replace Obama Care. Humana Inc. was one of the insurers who was active within Obama Care. It eventually dropped out of the insurance markets months later; but at the time it should have been affected by the uncertainty about future of Affordable Care Act (Obama care). Examine the price of Humana's stock prices 2 months before and 2 months after the election; did the election make a difference in percent of days the stock went up? Complete the analysis for every 6 days the market was open. Repeat the analysis and this time control for the Nasdaq index fund (as a surrogate of general economy) and Standard & Poor Healthcare Sector index (a surrogate for changes in the healthcare industry). After controlling for these two alternative explanations, did the election still affect percent of days stock went up?  Data► Chihiro's Slides► Chihiro's write up► Excel►



Copyright 1996 Farrokh Alemi, Ph.D. Most recent revision 09/20/2020.  This page is part of the course on Statistical Process Improvement, this is the lecture on Introduction to the Course.