1 | SAMPLING AND DATA Flashcards
Average
also called mean; a number that describes the central tendency of the data
Blinding
not telling participants which treatment a subject is receiving
Categorical Variable
variables that take on values that are names or labels
Cluster Sampling
a method for selecting a random sample and dividing the population into groups (clusters); use simple random sampling to select a set of clusters. Every individual in the chosen clusters is included in the sample.
Continuous Random Variable
a random variable (RV) whose outcomes are measured; the height of trees in the
forest is a continuous RV.
Control Group
a group in a randomized experiment that receives an inactive treatment but is otherwise managed
exactly as the other groups
Convenience Sampling
a nonrandom method of selecting a sample; this method selects individuals that are easily
accessible and may result in biased data.
Cumulative Relative Frequency
The term applies to an ordered set of observations from smallest to largest. The
cumulative relative frequency is the sum of the relative frequencies for all values that are less than or equal to the given value.
Data
a set of observations (a set of possible outcomes); most data can be put into two groups: qualitative or quantitative
qualitative data
an attribute whose value is indicated by a label
quantitative data
an attribute whose value is indicated by a number
Can be separated into two subgroups: discrete and continuous
discrete quantitative data
Data is discrete if it is the result of counting (such as the number of students of a given ethnic group in a class or the number of books on a shelf)
continuous quantitative data
Data is continuous if it is the result of measuring (such as distance traveled or weight of luggage)
Discrete Random Variable
a random variable (RV) whose outcomes are counted
Double-blinding
the act of blinding both the subjects of an experiment and the researchers who work with the subjects
Experimental Unit
any individual or object to be measured
Explanatory Variable
the independent variable in an experiment; the value controlled by researchers