A M I R B A D A M C H I

CASE-BASED REASONING CASE STUDY: HOUSING PRICE

Amirkabir University of Technology

Computer Engineering & Information

Technology Faculty

CONTENTS

• CBR

• Definition

• Assumptions

• Cycle

• Advantages, disadvantages

• Housing Price

• Introduction

• Method

• Estimation Function

• Similarity Function

• Results

DEFINITION

• Case-based reasoning is […] reasoning by remembering - Leake, 1996

• A case-based reasoner solves new problems by adapting solutions that were used to solve old problems - Riesbeck & Schank, 1989

• Case-based reasoning is a recent approach to problem solving and learning […] - Aamodt & Plaza, 1994

CBR ASSUMPTIONS

• The main assumption is that:• Similar problems have similar solutions:

• e.g., an aspirin can be taken for any mild pain

• Two other assumptions:• The world is a regular place: what holds true today will

probably hold true tomorrow • (e.g., if you have a headache, you take aspirin, because it has

always helped)

• Situations repeat: if they do not, there is no point in remembering them • (e.g., it helps to remember how you found a parking space near

that restaurant)

CBR CYCLE

• Retrieve:• Determine most similar case(s).

• Reuse:• Solve the new problem re-using information and

knowledge in the retrieved case(s).

• Revise:• Evaluate the applicability of the proposed

solution in the real-world.

• Retain:• Update case base with new learned case for

future problem solving

CBR CYCLE

ADVANTAGES

• solutions are quickly proposed• derivation from scratch is avoided

• domains do not need to be completely understood

• cases useful for open-ended/ill-defined concepts

• highlights important features

DISADVANTAGES

• old cases may be poor

• library may be biased

• most appropriate cases may not be retrieved

• retrieval/adaptation knowledge still needed

HOUSING PRICE

• Mary wishes to sell her apartment in the city.

• She might start with the price she paid for her

apartment and add an annual appreciation that

seems reasonable to her.

• She might try to predict market trends and figure

out how much the apartment should be worth.

HOUSING PRICE

• General rules

• In this area, the price per squared meter is $3,000..

• Case-based

• The apartment next door, practically identical to mine, was

just sold for $300,000..

METHOD

METHOD(CONT)

ESTIMATION FUNCTION

• Use parametric approach

• Advantages:

• Simplify to analyse

• Comparasion of two models

• Hyphotehes Test

SIMILARITY FUNCTION

• Weighted euclidean distance

• Why weighted euclidean distance instead standard

euclidean distance

• Variables with differenet scales

• Variables with differenet influent

• Allow a wide range of distance functions, weighing the

relative importance of variables

SIMILARITY FUNCTION

• Translate the distance function to a similarity

function

• decreasing in the distance

• The distance goes up from 0 to

• The similarity function goes down from 1 (maximal

similarity) to 0.

RESULTS

• Goodness of fit measures for regression and

similarity, for the two databases.

LIKE :Value of the log-likelihood function (in-sample, 75% of the data

points)

SSPE: Sum of Squared Prediction Errors (out of sample, remaining 25%

of the data points)

AIC: Akaike Information Criterion (computed over the whole sample)

SC : Schwarz Criterion (computed over the whole sample)

REFERENCES

• Ian Watson, “An Introduction to Case-Based

Reasoning”, 1995.

• Gayer, Gilboa, Lieberman,"Rule-Based and Case-

Based Reasoning in Housing Prices", 2007.

• Billot, A., I. Gilboa, D. Samet, and D. Schmeidler,

"Probabilities as Similarity-Weighted Frequencies",

2005.

Any question?

THAT’S ALL FOLKS!