Stats CH 2

Population

The entire group of individuals to which law of nature applies

Sample

A relatively small subset of a population that is intended to represent or stand in for the population.

Parameter

A number derived from a population

Sample (stats)

A number derived from the sample is a statistic

Descriptive stats

Are procedures for organizing and summarizing data-sample

Inferential stats

Are procedures for deciding whether sample data accurately represent a particular relationship in the population

Data

Are numbers or measurement that are collected as a result of observation. They are scores obtained in research

Quantitative data

The amount of a variable that is present

Qualitative data

an individual on the basis of some characteristic

Constant

Does not change

Variable

Anything that can or vary from one situation to another
(heat levels, test scores, height)

Measurement

The process of assigning number or labels to variables according to specific to represent characteristics or properties

Descriptive study

a study where we gather info about a topic of interest and accurately as possible
(U.S census data)

Correlational study

a study used to measure participants scores on two variables and then determine whether a relationship is present
(numbers of hours spent study, and test scores, exercising and cholesterol levels)

Experimental study

A variable is being changed or manipulate and is measured to see if that variable has a change on the other variable.
(effects of ADHD medication on the youth)

Quasi-experimental study

a type of research design that is similar to an experiment design that is similar to an experiment design except it lacks random assignment and a comparison group and a comparison group.

Independent variable

a variable that is changed or manipulated by the experiment
(an amount of fertilizer used on a plant in hopes of plant growth)

Manipulated I.V

an experiment that an experimenter deliberately changes or controls to see if it affects another variable.

Subject I.V (Quasi-Independent)

a characteristic of participants that can't be manipulated by the researcher but is still treated as an independent variable in the study
(age, chronic illness, gender)

Dependent variable

a variable that measures the effect of the independent variable
(plant growth after a certain amount of fertilizer is used)

Research design

a systematic procedure for collecting data in order to provide answers to specific questions. It is the way the study is laid out.

Continous data

measurable values that can take any value in a range (ex: time, height)

Condition

A specific amount or category of independent variable that creates the specific situation under which participants are examined. Also known as a level or treatment

Nominal

does not indicate an amount; rather, it is used for identification

(Hair color, political party)

Ordinal

indicates rank order. There is not an equal amount separating every pair of adjacent scores.

(Election results, class ranking)

Interval

and actual quantity and an equal amount separates adjacent scores. Interval scales do not have a true “0”

(Temperature, I.Q)

Ratio

reflects the true amount of the variable that is present because the scores measure an actual amount, there is an equal unit of measurement, and 0 truly means that none of the variable is present.

(Income, height)

Continuous scale

allows for fractional amounts and so decimals make sense

Discrete scale

only whole-number amounts can be measured

Discrete variable

only two possible categories or scores

(Male or female, yes or no, correct or incorrect)