Six Sigma Case Study
Online Top-Up for Prepaid Cellular Service

This Six Sigma case study looks at a cellular service provider's problems with their online top-up system and how the DMAIC process was used to fix it.

The Problem

In this six sigma case study, we look at a problematic online top-up system for a cellular service provider.

The top-up system had very low successful registration rates and well as very low successful top-up rates.

Registration success rate was hovering around 80% and Top-Up success rate was at about 60%.

This caused problems on two fronts. Firstly, customers were forced to call into the customer service center which cost extra time and money for the company. Secondly, the customer may decide not to top up at all which results in a loss of revenue. Worst, many customers who are put off may switch to providers which have hassle-free online top-up systems.

The Method

A small team was formed to find ways of increasing top up and registration success rates.

First of all the team brainstormed the inputs that could be affecting the success rate. There were only 9 inputs that were identified.

The next step was to figure out which inputs had a significant impact on the success rate. Hypothesis tests such as the Chi-Squared test were conducted to find significance.

The results of the tests were surprising. Inputs that should affect the output such as customer top up history did not have a statistically significant impact. Whereas factors which should not have any affect on the output, such as top up value, seemed to have a strong correlation.

This pointed strongly towards inconsistency in the rules and algorithm of the top up system.

New rules and procedures were created to follow logical and calculated decisions in accepting or rejecting a transaction. New criteria were also assigned for what could be a fraudulent transaction. IP addresses were also reviewed for black or white listing as many addresses were blacklisted without good cause.

The Result

The success rate of registrations moved up to 91%. Top-Up success rate went up to 90%. This resulted in over $300,000 per year in additional revenue.

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