How to Calculate the Overall Error Rate in Medical Transcription
Medical transcriptionists typically listen to dictated recordings made by medical professionals and create text files from the material. They use a headset and a special pedal for controlling the recording speed as they type. A good transcriptionist makes few mistakes, but no one's perfect. Typical errors include misspellings or wrongly inserted words. Since transcription errors occur on single words, you can determine a transcriptionist's overall error rate by calculating the percentage of words misspelled or misheard. Although more elaborate systems are available, this method provides a quick way for supervisors to evaluate the accuracy of their workers for purposes of performance evaluation.

Use the following equation for calculating the error rate as a percentage:
Error rate = (M/T) x 100 percent
M = number of mistakes in the form of misspellings or misheard words
T = total number of words in the sample 
Analyze a sample of the medical transcriptionist's work to determine the number of mistakes made and the total number of words. For instance, consider a document containing 500 words and 10 mistakes.

Input the numbers into the equation to calculate the transcriptionist's error rate:
Error Rate = (10/500) x 100 percent = 2 percent
This transcriptionist has a 2 percent error rate. An error rate of 2 percent or lower is an acceptable rate for noncritical information, according to the transcriptionists' professional association.
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