Excel: What-if Analysisseemeclt/what-if_analysis.pdf · 2016-08-30 · Excel: What-if Analysis Tutor: Pan Hong Date: Sep 8, 2016 . Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017

Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017

Excel: What-if Analysis

Tutor: Pan Hong

Date: Sep 8, 2016


Basic Data Analysis

Sorting

Filtering

Subtotal

Table

Pivot Table


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


What-if Analysis

Sensitivity Analysis

Decision Making

Constructed Mathematical Model

Outcome Evaluation

Influential Factors

Function Relation y = f (x1, x2, …)


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


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


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


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


Scenarios

Different with Data Table

more than two influential factors

Under Particular Circumstances

Combination of all arguments with special values


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


Scenarios Usage (2)

Modify Scenario Manager -> Edit

Delete

Merge Import Scenarios from other workbook or

worksheet

Display Scenario Manager -> Show

Volatile source data


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


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


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,…)


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


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


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


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


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)


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


Solution Analysis

Solver Report

Solver Parameters

Configuration: Solver Options

Max Time Running

Iterations

Tolerance

Precision

Convergence


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


Thanks!

Documents

Excel: What-if Analysisseemeclt/what-if_analysis.pdf · 2016-08-30 · Excel: What-if Analysis Tutor: Pan Hong Date: Sep 8, 2016 . Tutorial Series, MSc in SEEM/ECLT, 1st term, 2016-2017