Exam 1 Terminology

Question 1

Statistics

Answer 1

Statistics is a mathematical science pertaining to the collection, analysis, interpretation or explanation, and presentation of data. It is applicable to a wide variety of academic disciplines, from the physical and social sciences to the humanities. Statistics are also used for making informed decisions.

Question 2

Population

Answer 2

All members of a specified group.

Question 3

Sample

Answer 3

A subset of a population.

Question 4

Descriptive statistics

Answer 4

Descriptive statistics are used to describe the basic characteristics of the data in a study. They provide simple summaries about the sample being measured. They can be expressed in numerical and/or graphical form. They form the basis of virtually every quantitative analysis of data.

Question 5

Inferential statistics

Answer 5

Inferential statistics are used to draw conclusions about a population based on information contained in a sample. Information is obtained from a sample and generalized to a population. In this category of statistics, conclusions are made with incomplete information.

Question 6

Parameter

Answer 6

A value, or quantity, that represents a characteristic of a population such as the population mean or standard deviation.

Question 7

Statistic

Answer 7

A value, or quantity, that represents a characteristic of a sample such as the sample mean or standard deviation.

Question 8

Variable

Answer 8

Something that can take on more than one value. A variable might be expected to vary over time. Values of a variable would probably be expected to differ between individuals.

Question 9

“Levels” of a variable

Answer 9

The various values that a variable may assume. For example, red, white, and blue are among the levels of the variable “color.”Levels of the variable “G.P.A.” include: 2.5, 3.2, and 4.0.

Question 10

Quantitative variable

Answer 10

A variable whose levels are described numerically. Examples include temperature, % body fate, and time.

Question 11

Qualitative variable

Answer 11

A variable whose levels are described with words or phrases. Examples include color (red, white, blue), gender (female, male), and size (small, medium, large).

Question 12

Continuous variable

Answer 12

A quantitative variable that can be reduced to an infinite number of possible values, depending on the accuracy of the measuring instrument. Examples include height, weight, and distance.

Question 13

Discrete variable

Answer 13

A variable, either qualitative or quantitative, with a finite number of levels that cannot be subdivided meaningfully. Examples include heart rate, IQ, and color.

Question 14

Nominal Level of Measurement

Answer 14

Variable are categorical, qualitative, and discrete in nature. Although numbers can be used to represent levels of the variables, the numbers are treated as labels. Examples include brand of shoes, Social Security number, and gender.

Question 15

Ordinal Level of Measurement

Answer 15

Variables are categorical and discrete in nature. Unlike variables at the nominal level, variable levels at the ordinal level of measurement can be rank-ordered meaningfully. Examples include finish position in a race (1st ,2nd, 3rd..) and t-shirt size (S, M, L, XL).

Question 16

Interval Level of Measurement

Answer 16

Variables at this level may be quantitative or qualitative, discrete or continuous. They possess the characteristics of ordinal level variables with the added characteristic of equal intervals between levels. Examples include temperature (F), shoe size, and IQ.

Question 17

Ratio Level of Measurement

Answer 17

Ratio level variables possess all of the characteristics of interval level variables with the added characteristic of a measurement scale or an absolute absence in quantity of the variable being measured. Examples, measured quantitatively, include height, weight, and distance.

Question 18

Validity

Answer 18

The degree to which an instrument measures what it intends to measure.

Question 19

Reliability

Answer 19

The repeatability of a measurement. An instrument is reliable if it provides the same value consistently.

Question 20

Systematic variability

Answer 20

Variability in a measurement that is caused by something we can account for.

Question 21

Measurement error

Answer 21

The failure of identically treated subjects to elicit the same response.

Question 22

Unsystematic variability

Answer 22

Error, or variability in a measurement, that is caused by something we cannot account for.

Question 23

Establishing cause and effect

Answer 23

Four criteria:

1) The cause and effect must occur close together in time.
2) The cause must happen before the effect.
3) The effect should not happen without the presence of the cause.
4) No plausible alternate explanations exist.

Question 24

Tenacity

Answer 24

An unscientific method of problem solving in which people cling to certain beliefs regardless of the lack of supporting evidence.

Question 25

Intuition

Answer 25

An unscientific method of problem solving where a person has the ability to sense or know something without reasoning.

Question 26

Authority

Answer 26

An unscientific method of problem solving in which reference to an authority is used as a source of knowledge.

Question 27

Rationalistic method

Answer 27

An unscientific method of problem solving in which we derive knowledge through reasoning.

Question 28

Dependent variable

Answer 28

The outcome measure; the variable that is measured in a research study. It is affected by, or "dependent" on, the actions of other variables such as the independent variable(s).

Question 29

Independent variable

Answer 29

A variable that you identify as having a potential influence on your outcome measure. This might be a variable that you control, like a treatment. It also might represent a demographic factor like age or gender.

Question 30

Control variable

Answer 30

A control variable is held constant, or controlled, at one level throughout an experiment. For example, caloric intake would be controlled in a diet study; gender would be controlled in a strength study.

Question 31

Extraneous variable

Answer 31

Extraneous Variables are undesirable variables that influence the relationship between the variables that an experimenter is examining. These variables are undesirable because they add error to an experiment. A major goal in research design is to decrease or control the influence of extraneous variables as much as possible.

Question 32

Representative sample

Answer 32

A representative sample reflects the characteristics of interest from the target population.

Question 33

Random sample

Answer 33

A random sample is drawn in such a way that all members of the population have an equal chance of being selected. This type of sampling is only occasionally used in research with human subjects.

Question 34

Biased sample

Answer 34

A biased sample is drawn in such a way that some members of the population are more likely to be chosen than others.

Question 35

Convenience sample

Answer 35

A convenience sample is drawn from an “intact class” or by asking people to volunteer. The sample is not randomly chosen and is typically used because of the ready availability of the subjects. This is a biased sample.

Question 36

Stratified sample

Answer 36

A sample chosen from a population that has been subdivided based upon predetermined characteristics such as gender, race, and socio-economic status. This is the sampling method used for many nationwide polls.

Question 37

Systematic sample

Answer 37

A sample obtained using a pre-determined system (not random); for example, choosing every 10th subject from the population.

Question 38

Retrospective study (case-control study) (cross-sectional study)

Answer 38

Data is examined from selected cases and controls to determine differences, if any, in the exposure to a suspected factor. Subjects are not “treated,” variables are not controlled, and cause & effect may not be inferred. Example: Incidences of premature births were counted among mothers who smoked (case group) and mothers who didn’t smoke (control group).

Question 39

Prospective study (cohort study) (longitudinal study)

Answer 39

A group of healthy subjects is enrolled and followed over time to determine the frequency with which a specific outcome develops. The sample may be grouped according to the presence or absence of a stimulus variable such as smoking history. Example: A group of smokers and a group of non-smokers were observed across time with the intent of comparing the incidence of lung disease.

Question 40

Experiment (clinical trial)

Answer 40

A carefully designed study that seeks to determine, under controlled conditions, the effectiveness of a treatment method.

Question 41

Random Assignment

Answer 41

The process whereby subjects are randomly assigned to treatment and control groups. This is not random sampling – it occurs after the sample has been chosen.

Question 42

External validity

Answer 42

The degree to which the experimental results can be generalized to the target population. The highest degree of external validity exists when all responses from subjects in the sample can be seen in the population. For example, an average loss of 10 pounds in the sample would be mirrored by an average loss of 10 pounds in the population.

Question 43

Internal validity

Answer 43

The degree to which changing the level of the independent variable causes a change in the dependent variable. In an experiment, the highest degree of internal validity exists when all changes in the dependent variable can be attributed to the effect of the independent variable.

Question 44

Avis Effect

Answer 44

The Avis effect occurs when subjects in a control group discover they are in a control group and they react by “trying harder.” This is a threat to the internal validity of a study.

Question 45

Placebo Effect

Answer 45

The measurable, observable, or felt improvement in health or behavior not attributable to a medication or treatment that has been administered.

Question 46

Hawthorne Effect

Answer 46

The Hawthorne effect occurs when subjects in a treatment group improve their performance because they are aware they are being treated or tested. This is a threat to the internal validity of a study.

Question 47

Single-blind study

Answer 47

A study in which the subject does not know whether he or she is in the treatment or control group.

Question 48

Rosenthal Effect

Answer 48

The Rosenthal effect occurs when a researcher inadvertently influences subjects’ performances, which consequently affects the outcome of a study. This is a threat to the internal validity of a study.

Question 49

Double-blind study

Answer 49

A study in which neither the subject nor the experimenter knows to which group the subject has been assigned.