# BIOSTATISTICS FOR USMLE

 Statistics deals with the world as distributions 1.Mean definition and how to calculate it... 2.Median defintion and how to get it... 3.Mode definition and how to get it... Mean: average. (sum of results of observations/number of observations) Median: Value at the 50th percentile. if you have an even set of values, take the average of the two values around 50th percentile. Mode: More frequent value 1. NEGATIVELY SKEWED DISTRIBUTION CURVE, the tail goes to the? 2. POSITIVELY SKEWED DISTRIBUTION CURVE, the tail goes to the? 1. LEFT.2. RIGHT. Standard Deviation is a stable measure of dispersion What do you need to know for the exam about this? That in any normal curve there is a constant proportion of cases that fall within 1,2, and 3 SD's 1 SD: 68% of the cases.2 SD: 95.5% of the cases.3 SD: 99.7% of the cases. So, Here is the graphic you need to Memorize!! EXAMPLES? BRING IT!! In a normal distribution curve, what percent of the cases are below 2 SD's below the mean? 2.5% In a normal distribution curve, what percent of the cases are above 1s below the mean? 84% A student took 2 tests: On which test did the student better. Test A AuthorCamilomd ID62913 Card SetBIOSTATISTICS FOR USMLE DescriptionBiostatistics key points or USMLE Updated2011-01-30T16:04:19Z Show Answers