| Term 
 
        | Measures of Central Tendency |  | Definition 
 
        | - descriptors of what is average in a sample group |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | also called the average:  sum of the scores (x) divided by the number of items (n). |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - the most common number or the number having the highest frequency in a set of measurements |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - the counted middle or the midpoint number when a series of measurements are arranged in order |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | the way scores differ, vary, disperse around the mean |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - spread between the highest and lowest score; (limited usefulness; must first be displayed in ascending order) |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - measure of the average deviation or spread of scores around the mean |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - used to analyze descriptively the spread of scores in a distribution; the greater the dispersion of scores around the mean, the greater the SD; mathematically speaking, it is the positive square root of the variance |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - Divides the data into 4 parts centered on the median |  | 
        |  | 
        
        | Term 
 
        | Lower quartile/25% percentile |  | Definition 
 
        | - number below which 25% of the data points fall |  | 
        |  | 
        
        | Term 
 
        | Upper quartile/75th percentile |  | Definition 
 
        | - number above which 25% of the data points fall |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - A description of the spread or variation (i.e. smallest to largest) of the data points in a data set |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - In any normal distribution, 68% of the data points or observations fall within one standard deviation of the mean, 95% fall within two standard deviations, and 99.7% fall within three standard deviations of the mean. |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - relationship between risk factors and disease |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - implication that the risk factor(s) cause(s) the disease or outcome observed |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - used in case-control / retrospective studies, measures the odds of having the risk factor if the disease is present |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - in prospective studies; measures the risk that an individual will develop an adverse outcome over a specified time given the exposure |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - The probability that a condition will be correctly identified by a test or index.  The ability to detect a quality if it is present |  | 
        |  | 
        
        | Term 
 | Definition 
 
        | - Ability of a test to distinguish between those who do and do not have a disease or condition |  | 
        |  |