Tuesday, January 17, 2012

LOGISTIC REGRESSION IN MARKETING DEPARTMENT



Suppose the marketing department wants to launch a new product (see picture) on the market. After select the design of the product and decide about the taste of the product in the laboratory, how can we be sure that the product will be admitted by the consumers?  Machine learning can help you take good decision about the tasting and the design of the product.
A sampling of consumer taste and score over 100 about the tasting and the designing of our product. At the end of the test they admit or not to sell the product.
Set Sample of the population
Tasting Score
Design Score
Y
34,62365962
78,02469282
0
30,28671077
43,89499752
0
35,84740877
72,90219803
0
60,18259939
86,3085521
1
79,03273605
75,34437644
1
45,08327748
56,31637178
0
61,10666454
96,51142588
1
75,02474557
46,55401354
1
76,0987867
87,42056972
1
84,43281996
43,53339331
1
95,86155507
38,22527806
0
75,01365839
30,60326323
0
82,30705337
76,4819633
1
69,36458876
97,71869196
1
39,53833914
76,03681085
0
53,97105215
89,20735014
1
                                               Source: Adapted from Stanford ML Course
Data visualization
We first of all realize that in general a product with more than 50% designing score and more than 50% score tasting is selected to be admitted.


Logistic regression is one of the most useful supervise technique in classified problem.  This method is used here to answer the question.
The coefficients of the model are Theta_0=-25.16; Theta_1=0.206 and Theta_2=0.201 this shows that our variables (tasting score and designing score) affect positively the admission of the product.
Misclassification matrix
Predicted Value
Not Admitted
Admitted
Total
Not Admitted
35
5
40
Admitted
5
55
60
Total
40
60
100

The model misclassified 8% of admitted product and 12.5% of not admitted product. Globally, the error rate is 10% ((5+5)/100) and the overall accuracy rate is 90% ((35+55)/100). This means that we have 90% of chance to predict according to the model that a product will be admitted in the market.

The decision boundary of the model is drawn in the following figure. The figure implies that all points over the boundary line are predicted to be admitted and others are predicted to be not admitted. The model predicts four false positive (points that are negative and the model predict that they are positive) and five false negative (points that are positive and model predicts that they are negative).  

Application of the model to predict the admission of a product with a tasting score of 50 and a designing score of 90, the admission probability is 96.38%

No comments:

Post a Comment