Sampling and Data

Question 1

Average (Mean)

Answer 1

A number that describes the central tendency of the data.

Question 2

Blinding

Answer 2

Not telling participants which treatment a subject is receiving.

Question 3

Categorical Variable

Answer 3

Variables that take on values that are names or labels.

Question 4

Cluster Sampling

Answer 4

A random sampling method: divide population into clusters, randomly select clusters, and include all individuals in selected clusters.

Question 5

Continuous Random Variable

Answer 5

A random variable whose outcomes are measured; e.g., the height of trees.

Question 6

Control Group

Answer 6

A group in a randomized experiment receiving an inactive treatment but otherwise treated like other groups.

Question 7

Convenience Sampling

Answer 7

A nonrandom sampling method selecting easily accessible individuals; can lead to bias.

Question 8

Cumulative Relative Frequency

Answer 8

The sum of relative frequencies for all values ≤ a given value in an ordered dataset.

Question 9

Data

Answer 9

A set of observations; can be qualitative (labels) or quantitative (numbers). Quantitative data may be discrete (counting) or continuous (measuring).

Question 10

Double-blind Experiment

Answer 10

An experiment where both subjects and researchers are unaware of the treatment assignments.

Question 11

Experimental Unit

Answer 11

Any individual or object to be measured in a study.

Question 12

Explanatory Variable

Answer 12

The independent variable controlled by researchers in an experiment.

Question 13

Frequency

Answer 13

The number of times a data value occurs.

Question 14

Informed Consent

Answer 14

Human subjects must understand the study’s risks, benefits, and procedures, and agree freely to participate.

Question 15

Institutional Review Board (IRB)

Answer 15

A committee that oversees research involving human subjects to ensure ethical conduct.

Question 16

Lurking Variable

Answer 16

A variable that affects the study outcome but is neither explanatory nor response.

Question 17

Nonsampling Error

Answer 17

Errors affecting data reliability not due to sampling variation; includes design flaws, bias, and human errors.

Question 18

Numerical Variable

Answer 18

Variables with values indicated by numbers.

Question 19

Parameter

Answer 19

A number representing a population characteristic; often not directly measurable.

Question 20

Placebo

Answer 20

An inactive treatment with no real effect, used as a control in experiments.

Question 21

Population

Answer 21

All individuals or items being studied.

Question 22

Probability

Answer 22

A number between 0 and 1 representing the likelihood of a specific event.

Question 23

Proportion

Answer 23

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

Question 24

Qualitative Data

Answer 24

Observations with values indicated by labels (categories).

Question 25

Quantitative Data

Answer 25

Observations with numerical values; can be discrete (counted) or continuous (measured).

Question 26

Random Assignment

Answer 26

Assigning experimental units to treatment groups using random methods.

Question 27

Random Sampling

Answer 27

Every population member has an equal chance of being selected.

Question 28

Relative Frequency

Answer 28

The ratio of a value’s frequency to the total number of outcomes.

Question 29

Representative Sample

Answer 29

A subset of the population that reflects the population’s characteristics.

Question 30

Response Variable

Answer 30

The dependent variable measured for change in an experiment.

Question 31

Sample

Answer 31

A subset of the population under study.

Question 32

Sampling Bias

Answer 32

Occurs when not all population members are equally likely to be selected.

Question 33

Sampling Error

Answer 33

Natural variation from sampling; decreases as sample size increases.

Question 34

Sampling with Replacement

Answer 34

After selection, a member is returned to the population before the next selection.

Question 35

Sampling without Replacement

Answer 35

A selected member is not returned to the population for further selection.

Question 36

Simple Random Sampling

Answer 36

Assign numbers to population members; use a random number generator to pick your sample.

Question 37

Statistic

Answer 37

A numerical characteristic of a sample used to estimate a population parameter.

Question 38

Stratified Sampling

Answer 38

Divide population into strata, then randomly sample proportionally from each group.

Question 39

Systematic Sampling

Answer 39

List all individuals; randomly choose a starting point, then select every kth individual.

Question 40

Treatments

Answer 40

Different values or conditions of the explanatory variable in an experiment.

Question 41

Variable

Answer 41

A characteristic of interest for individuals or objects in a population.

Question 42

Statistics

Answer 42

The science of collecting, organizing, analyzing, and interpreting data.

Question 43

Probability

Answer 43

A tool used in statistics to measure the likelihood of certain outcomes.

Question 44

Population vs. Sample

Answer 44

Population: the whole group; Sample: a representative subset used to draw conclusions.

Question 45

Types of Data

Answer 45

qualitative, quantitative continuous, or quantitative discrete.

Question 46

Variation in Sampling

Answer 46

Even representative samples differ. Larger samples better represent the population.

Question 47

Sampling Methods

Answer 47

Include random (simple, stratified, cluster, systematic) and nonrandom (convenience) methods.

Question 48

Critical Analysis of Data

Answer 48

Statistics must be analyzed critically to identify errors or biases.

Question 49

Rounding Rules

Answer 49

Round results to one more decimal place than the original data.

Question 50

Nominal Scale

Answer 50

Data with no order or numerical meaning.

Question 51

Ordinal Scale

Answer 51

Ordered data where differences are not measurable.

Question 52

Interval Scale

Answer 52

Ordered data with measurable differences but no true zero.

Question 53

Ratio Scale

Answer 53

Ordered data with measurable differences and a true zero point.

Question 54

Experimental Design

Answer 54

Well-designed studies use random assignment and control groups to isolate treatment effects.

Question 55

Ethical Considerations

Answer 55

Ethical issues arise when actions benefit some while harming others or violating rules.

Answer 56

qualitative, quantitative continuous, or quantitative discrete.