Biostatistics Introductory Terms

Goal of statistics

to learn about a large group of individuals simply by studying the data that we collect from a smaller subset of its members; draw conclusions about a small group from a more manageable subset

data

any information that we collect from the people involved in our study

population

the entire or complete group of people, items, etc., that we are interested in studying

• these vary in size

• Ex: all undergraduate students at Duquesne

sample

a smaller subset of the population

parameter

a measurement that describes a fact or characteristic of a population

• actual values for the entire population

statistic

a measurement that describes a fact or characteristic of a sample

• best estimate of entire population

qualitative variables (or categorical)

used to separate data into different categories that are distinguishable by some non-numeric characteristic

• used to classify or categorize

• limited computations

• Ex: ethnicity, hair color, political party affiliation

quantitative variables

variables that take numerical values for which arithmetic operations such as adding and averaging make sense

• Ex: height, weight, age

discrete variable

a variable characterized by gaps or interruptions in the values that it can assume

• restricted to a set of values that possess gaps (must be finite numbers)

• Ex: # of daily admissions to a local hospital

continuous variable

a variable that can take on any value in a specified interval

• no GAPS (can be decimal numbers)

• Ex: amount of daily rainfall