11th and 12th session - group F

KANYA PATIL-14021

In the 11^th and 12^th session of BA we learnt about what is Multi-dimensions scaling. In this there are 2 methods.

a)      Overall Similarity – The main advantage of overall similarity method is that, it throws up latent attribute that may not always be considered or known to us.

It is where we present the respondents with different pairs of objects and ask how similar or dissimilar the objects are.

The disadvantage of overall similarity is that it needs complete knowledge to interpret.

b)      Attribute Based – The main advantage of attribute based method is that, it is easy to execute. In this method we ask people to rank attributes and map them. The disadvantage is that there is a threat of missing important attribute.

In today’s session, we mapped the variable ‘‘store satisfaction’’ for 4 stores based on 6 attributes. Quality satisfaction, price satisfaction, etc. The proximity matrix looks like this:

            Title- Store Satisfaction

            nObjects - 4

            nAttributes - 6

            Attribute List

            Store 1  3.01     3.08     3.25     3.18     3.17     2.99

            Store 2  3.21     3.10     2.94     2.88     3.31     3.00

            Store 3  3.16     3.09     3.23     3.30     3.08     3.31

            Store 4  2.97     3.04     3.31     3.01     3.08     3.07

The PERMAP looks like this.

We also studied Distance Matrix, Similarity Matrix and Dissimilarity Matrix.

1)      Distance Matrix: In mathematics, computer science and graph theory, a distance matrix is a matrix (two-dimensional array) containing the distances, taken pairwise, of a set of points. This matrix will have a size of N×N (where N is the number of points, nodes or vertices

2)      Similarity Matrix: In this, diagonals will always contain 1. For example, in mobile users we saw that sms, alarm, time&date, games come together because of highest number of yes matches, since we use binary variables and jaccard method.

3)      Dissimilarity Matrix: In this, diagonals will always contain 0. For example, in distance between cities, where we used Euclidean distance, the distance between a city and itself will always be 0.

Permap Software:

PERMAP is a free, Windows-based real-time interactive program for making perceptual maps also called product maps, strategic maps, sociograms, sociometric maps, psychometric maps, stimulus-response maps, relationship maps, concept maps, etc. Its fundamental purpose is to uncover any "hidden structure" that might be residing in a complex data set. PERMAP takes object-to-object proximity values (similarities, dissimilarities, correlations, distances, interactions, psychological distances, dependencies, confusabilities, preferences, joint or conditional probabilities, etc.), or up to 30 object attribute values, and uses multidimensional scaling (MDS) to make a map that shows the relationships between the objects. Succinctly, it makes classical metric and nonmetric MDS analyses in one, two, three, … or eight dimensions, for one-mode two-way or two-mode two-way data, with up to 1000 objects and with missing values allowed. In addition, it can make several new types of MDS analyses involving error bounds or boundary conditions and it can show the affect of degrading the similarity information.