##### PSY 241 - Module 1 Key Terms

Average/Mean

a number that describes the central tendency of the data

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.

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

Frequency

the number of times a value of the data occurs

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.

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

Parameter

a number that is used to represent a population characteristic and that generally cannot be determined easily

Placebo

an inactive treatment that has no real effect on the explanatory variable

Population

all individuals, objects, or measurements whose properties are being studied

Probability

a number between zero and one, inclusive, that gives the likelihood that a specific event will occur

Proportion

the number of successes divided by the total number in the sample

Random Assignment

the act of organizing experimental units into treatment groups using random methods

Random Sampling

a method of selecting a sample that gives every member of the population an equal chance of being selected.

Relative Frequency

the ratio of the number of times a value of the data occurs in the set of all outcomes to the number of all outcomes to the total number of outcomes

Representative Sample

a subset of the population that has the same characteristics as the population

Response Variable

the dependent variable in an experiment; the value that is measured for change at the end of an experiment

Sample

a subset of the population studied

Sampling Bias

not all members of the population are equally likely to be selected

Sampling with Replacement

Once a member of the population is selected for inclusion in a sample, that member is returned to the population for the selection of the next individual.

Sampling without Replacement

A member of the population may be chosen for inclusion in a sample only once. If chosen, the member is not returned to the population before the next selection.

Variable

characteristic of interest for each person or object in a population

Qualitative Data

an attribute whose value is indicated by a label

Quantitative Data

an attribute whose value is indicated by a number

Discrete 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 Data

Data is continuous if it is the result of measuring (such as distance traveled or weight of luggage)