Using The Confidence Interval in Six Sigma Methodology

A leading market research firm conducts a survey among voters in the United States asking who they would vote for if the election was today. The answers are surprising, showing favor for an independent candidate who is actually expected to secure only 23% of the votes. This firm could then be asked to prove the accuracy of these findings. They might respond by saying they are 95% confident this independent candidate will secure 23% of the votes. This confidence, however, will come with a plus or minus alternative, meaning he will receive 23% plus or minus 2 percent of the vote. confidence interval calculator Where statistics are concerned, what they are saying is that he will end up with a vote ranging between 21 and 25 percent. This is what is known as the confidence range. The 95 percent level explains the probability of this occurring.

A confidence interval provides an estimated range of values that is likely to include some population parameter that is unknown. The estimated range is then calculated from a given set of sample data. If independent samples are repeatedly extracted from the same population, and a confidence interval is calculated from each, a certain percent confidence level of the intervals will include the unknown parameter from the population from which it was drawn.

The confidence intervals are usually calculated so this percentage is at 95 percent; however, it is possible to produce intervals of 99 percent, 99.9 percent, 90 percent etc..

Six Sigma provides many different tools that can be used for statistical purposes such as the example illustrated above. The market research firm would have calculated the 95 percent confidence interval from data that was collected and used based on their survey results. This information can then be used to make important determinations and answer questions using the confidence interval and Six Sigma methodology. Together they can provide useful information that can help businesses or organizations further their endeavors.

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