excel: what-if analysisseemeclt/what-if_analysis.pdf · 2016-08-30 · excel: what-if analysis...
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Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Excel: What-if Analysis
Tutor: Pan Hong
Date: Sep 8, 2016
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Basic Data Analysis
Sorting
Filtering
Subtotal
Table
Pivot Table
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Advanced Analysis
Data Table 模拟运算表
Scenarios 方案
Goal Seeking 单变量求解
Solver 规划求解
Analysis ToolPak 分析工具库
Statistics
What-if Analysis
Add-Ins
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
What-if Analysis
Sensitivity Analysis
Decision Making
Constructed Mathematical Model
Outcome Evaluation
Influential Factors
Function Relation y = f (x1, x2, …)
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Single-Variable Data Table (1)
Create
Step1. Create a List (values for substitution)
Step2. Interested outcome declaration
Formula definition
Step3. Range selection (including the list)
Data -> What-if Analysis -> Data Table
Row / Column Input Cell: the single variable
The cell substituted with varying values
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Single-Variable Data Table (2)
Clear or Delete
Horizontal Data Table
Multi-formula Table
Format Number: concurrency
Field name defining: readability
Table refresh
Input cell modified: automatic calculation
Cells inside: non-revisable
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Double-Variable Data Table
Two influencing factors
Create Row input cell
Column input cell
Note: only one destination cell Table Refresh: formula modified
Used to solve equation Row input cell and column input cell defined as two
dependent variables
Row list and column list include the possible values
Outcome formula refers double-variable
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Feature of Data Table
Contrast with General Method (range) Define formula and then copy
Data Table Data as a whole part
Formula defined uniformly
Unable to modify single cell in particular
No need to consider absolute or relative reference
Arguments in formula: column or row input cell reference
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Scenarios
Different with Data Table
more than two influential factors
Under Particular Circumstances
Combination of all arguments with special values
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Scenario Usage (1)
Data -> What-if Analysis -> Scenario Manager Formulas -> Defined Names: Create from Selection: left
column (optional)
Create Scenario Manager -> Add
Name
Changing cells Press Ctrl for non-adjacent cells selection, less than 32
Comment Creator name and date by default
Protection
Enter Values
Note: worksheet based
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Scenarios Usage (2)
Modify Scenario Manager -> Edit
Delete
Merge Import Scenarios from other workbook or
worksheet
Display Scenario Manager -> Show
Volatile source data
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Scenarios Usage (3)
Generate Scenarios Report
Scenario Manager -> Summary
Report type
Scenario summary
Scenario Pivot Table report
Result cells
Recommendation by default
Press Ctrl for non-adjacent cells selection
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Comparison
Similarity
Perform value substitution to evaluate the outcome changes
Difference
Data Table: Assign a value sequence to one or two independent variables
Scenarios: Assign an individual value to a series of independent variables
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Reverse What-if Analysis
Desired result fixed, to find conditions on influential factors
Goal seeking: single variable
y = f(x)
Solver: more than one variable
y = f(x1,x2,…)
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Goal Seeking
Desired result from a single formula known, to find the determined input value
Function relation y = f(x)
x = f-1(y) f-1:inverse function
Excel: adjusts the value in one specific cell until the dependent formula reaches the result
Note Solution: possibly no existence
Configuration File -> options -> Formulas -> Calculation: maximum iterations
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Goal Seeking Usage
On Worksheet Data Data -> What-if Analysis -> Goal Seek…
Set cell To value By changing cell
On Chart (Only for Version_2003) Data Point selection: destination Drag and drop
Equation Solving Blank cell: independent variable naming x (Note: Scope) Formula input Goal seeking: destination value to 0
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Solver
Optimization: find the best way to do something
Mathematically: max/min f(x1,x2,…)
In excel Find the values of certain cells in a spreadsheet
that optimize a certain objective
Not launched by default Install: File ->Options -> Add-Ins -> Manage Excel Add-
ins -> Go: Solver Add-In
Use: Data -> solver
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Create Model
Target cell Objective
Maximum profit
Minimum cost
Changing cells Decision variables: value adjusting
Function relation with target cell
Constraints Restriction placed on changing cells
Represented with equations or in-equations
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Example
A company need to buy 4 kinds of gifts, with different unit prices, to do promotion. Quantity of each kind of gift must reach some requirements. Try to minimize the total cost.
Model Variables: x1,x2,x3,x4
Conditions x1≥ 400, x2≥ 600, x3≥ 800, 200≤ x4 ≤1000 x1 + x2 + x3 + x4 = 4000
Goal Min(c1*x1+c2*x2+c3*x3+c4*x4)
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Solver Usage
Data in a table
Solver parameters
Set Target Cell
Equal To
By Changing Cells
Subject to Constraints
Add
Solve
Solver Results
Save Scenario
Reports Selection
Answer
Sensitivity
Limits
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Solution Analysis
Solver Report
Solver Parameters
Configuration: Solver Options
Max Time Running
Iterations
Tolerance
Precision
Convergence
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Note
Existence of Answer Feasible Solution Optimal Solution
Limits Optimal? Initial values of decision variables on non-linear
programming deeply impact the final result
Professional solver Frontline Systems, Inc Upgrade the Excel Solver
Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017
Thanks!