ONE GOOD IDEA

# Easy A

## Tips for acing your certification exam

by William A. Levinson

It is almost as easy to fail a certification exam by making mistakes while answering questions—even if you know the answers—as it is to fail by not mastering the body of knowledge. While 100% error-proofing is not possible in such a context, the following tips help address the most easily preventable mistakes during a certification exam.

The human brain is designed to understand sentences and paragraphs without pausing to read every word. This ability can be dangerous on a certification exam, though; so it is important to read every word.

For example, the Quality Council of Indiana’s Six Sigma Green Belt Primer includes a question on whether a new process has changed the yield of a chemical. The word "yield" in context with "new process" implies a one-sided hypothesis test for an improvement or increase, but "changed" actually indicates a two-sided test.

We have also seen sample problems that require identification of a formula, such as

It is easy to get this question incorrect by answering "binomial distribution" based on the formula’s familiar appearance. The correct answer is actually "none of the above" because it is neither the binomial nor any other distribution. It is therefore crucial to pay close attention to everything in a question.

2. Error-proof averages and standard deviations.

A hand calculator can find the average and standard deviation of a set of numbers (be sure to use the σn-1 key for the average of a sample as opposed to a population). Use the calculator carefully, as the smallest error can result in an incorrect answer. The most likely data entry errors on a calculator include:

• A misplaced decimal point, which multiplies or divides a measurement by 10.
• Pressing an adjoining key for the first digit—for example, entering 14.3 or 34.3 instead of 24.3. The latter error in a trailing digit is unlikely to result in selection of an incorrect answer.

In the case of either of these errors, the average is likely to be less than the smallest measurement or larger than the greatest, which is, of course, impossible. Meanwhile, the standard deviation is likely to exceed the sample range considerably. These checks can be made quickly, and either situation should warn the examinee that he or she may have made a keystroke error.

3. Draw the test distribution.

A quick sketch of the test distribution can often detect an error in the interpretation of a hypothesis test. Draw the curve (it doesn’t need to be neat or accurate), and then mark the positions of the test statistic and its critical value. If the test statistic is outside the critical value—for example, it’s less at the left side and greater at the right side—reject the null hypothesis. The test statistic and its critical value must also be on the same side of the median for interpretation purposes.

It is good practice to skip problems you cannot solve quickly and then come back to them later. It is easy to envision a situation, though, in which the examinee skips problem No. 9 but then records the answer to problem No. 10 in the oval for No. 9. If this goes undetected, a considerable amount of erasing will be required. Therefore, it’s is important to always cross-check the number of the problem in the exam booklet with the line on the answer sheet.

In many cases, one or even two answer options are obviously wrong or defy common sense—they are distracters. The examinee can, even in an area in which he or she is weak, improve the chances of a correct guess by crossing off the choice(s) that are clearly incorrect.

Complete error-proofing of a certification exam is an impossible feat. These simple precautions can help to minimize the number of preventable errors made during an exam to help maximize your chances of passing and becoming certified.

William A. Levinson is principal consultant at Levinson Productivity Systems P.C. in Wilkes-Barre, PA. He has a master’s degree in engineering from Cornell University in Ithaca, NY, and an MBA from Union College in Schenectady, NY. An ASQ fellow, Levinson is an ASQ-certified quality manager, auditor and engineer, reliability engineer and Six Sigma Black Belt.

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