Statistics

Statistics

1.4 Basic Terms

• Statistician : Is someone who specializes in the field of statistics. It is often the job of the statistician to develop experimental designs, organize and analyze data, and generate graphical interpretations of the data. Statisticians are often hired by hospitals, pharmaceuticals, universities, insurance companies, and government agencies. • Quantitative : An objective measurement based on numerical values of a given data set or population. Examples of quantitative data are the average age of a population or the number of male students in a given class. • Qualitative : A subjective measurement based on opinion and non-numerical values. Examples of qualitative measurements would be color preference. “I prefer the color red to the color blue” is a qualitative assessment based on an individual’s opinio n or preference. It does not hold any numerical value. There are two types of statistics: descriptive and inferential statistics. Each plays an important unique role in the final interpretation of the data set. • Descriptive statistics : Uses quantitative measurements to objectively describe a data set. For example, descriptive statistics can use numerical values collected to describe the average age of a given population; or the success rate of a trial clinical therapy. • Inferential statistics : Uses qualitative measurements to make subjective interpretations about a given group. For example, if you were to ask a single class of college freshmen what their favorite color was and 75% of the class responded that their favorite color was blue, we could infer that the majority of college freshmen prefer the color blue. We are inferring this single observation to an entire population but do not have data for the entire population. Therefore, our inferential statistics is subjective and may change as we survey more college freshmen in additional classes. *Tip: Descriptive statistics tends to yield a more solid interpretation of the entire population. Inferential statistics tend to be subjective to change.

1.5 Measurements

Mean : The most general definition of mean is the calculated average of the given population or set of values. The mean, or average, can yield useful information about a population or given data set. From this calculation, we can determine the average age or average response. The formula for calculating the mean is:

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