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 type of random variable that can take on an infinite number of possible values within a given range. These values are typically real numbers and can include any value within an interval or across multiple intervals.
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.
Common Statistical Study Problems
- Sample problems (representative)
- Self-selected samples
- Sample size issues
- Undue influence
- Non-response or participation refusal
- Undue influence
- Causality (a relationship does not mean one causes the other to occur)
- Self-funded/Self-Interest studies
- Misleading use of data
- Confounding
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);
- Lowercase letters (e.g., x, y) are generally used to represent data values
Descriptive Statistics
Organizing and summarizing data is
Double-blind experiment
an experiment in which both the subjects of an experiment and the researchers who work with the subjects are blinded
Experimental Unit
any individual or object to be measured
Explanatory Variable
the independent variable in an experiment; the value controlled by researchers
Frequency
the number of times a value of the data occurs
Inferential Statistics
uses probability to determine how confident we can be that our conclusions are correct.
Informed Consent
Any human subject in a research study must be cognizant of any risks or costs associated with the study. The subject has the right to know the nature of the treatments included in the study, their potential risks, and their potential benefits. Consent must be given freely by an informed, fit participant.
Institutional Review Board
a committee tasked with oversight of research programs that involve human subjects
Level of measurement
The way a set of data is measured - data are classsified in four levels
- Nominal scale
- Ordinal scale
- Interval scale
- Ratio scale
Lurking Variable
a variable that has an effect on a study even though it is neither an explanatory variable nor a response variable
Nominal Scale
Qualitative (Categorical) data and cannot be ordered
Nonsampling Error
an issue that affects the reliability of sampling data other than natural variation; it includes a variety of human errors including poor study design, biased sampling methods, inaccurate information provided by study participants, data entry errors, and poor analysis.
Numerical Variable
variables that take on values that are indicated by numbers
Ordinal Level
Similar to nominal scale but can be ordered (e.g., list of top 5 banks in the U.S.)