AP Statistics Chapter 1-2 Vocab

Population

The specific group of items/people that is being studied

Statistic

A specific calculated value that describes a certain characteristic of a given sample

Parameter

A value that describes a characteristic for the whole population

Sample

A small group of a whole population used to study the larger population

Sample Survey

The use of a sample to study and make inferences about the larger population

Controlled Experiment

An experiment that changes certain factors to study changes on another variable while keeping outside elements constant

Observational Study

An experiment where no variables are changed and are only affected by natural causes

Selection Bias

Bias where the sample does not accurately represent the larger population

Response Bias

Bias where participants in a study wrongly answer questions leading to an incorrect representation of the population

2-Way Tables

A type of table that involves rows and columns with the rows representing categories of one variable and the columns representing categories of a different variable

Measures of Center

A single value that aims to represent the entire population with a central number(Mean, Median, Mode)

Measures of Spread(Variability)

A number that measures how disperse the data is and how well the Measure of Center represents the population

Descriptive Statistics

Category of statistics that involves organizing and summarizing data

Inferential Statistics

Category of statistics that observes a sample from a population to make generalizations and determining the error in the generalizations

Explanatory(Independent) Variables

A causal variable that can influence changes in a dependent variable

Response(Dependent) Variable

A variable measured to see if it was affected by a change in the independent variable

Random Sampling Methods

Process of selecting a sample that minimizes bias and most accurately represents the population

Measures of Position

Description of where a specific data point falls in relation to others(Z-Score, Quartiles, Percentiles)

Placebo

A substance with no effect given to a group to determine psychological beliefs of the effectiveness

Census

Complete collection of data from every individual in a given population

Treatments/Experimental Condition

Specific change in an independent variable that is used to measure the effect on the dependent variable

Blocking

A certain way of grouping samples into “blocks” based on a certain variable(age, gender)

Blinding

Process of withholding information from study participants and/or researchers to avoid skewing data

Sample Space

All possible outcomes for a given event

Probability

The likelihood of an event occurring

Sample Mean

Average value for a sample

Population Mean

Average value for a population

Univariate Data Set

Data set centered around a single characteristic

Categorical Data Set

Data set with categorical(Qualitative) data

Numerical Data Set

Data set with numerical(Quantitative) data

Discrete Numerical Variable

Possible data with isolated points that cannot form an interval

Continuous Numerical Variable

Possible data that could occur anywhere within an interval on a number line

Frequency

The number of times a certain element appears in a data set

Relative Frequency

The frequency of an element in relation to the total number of elements observed

Observational Study

A study where a specific characteristic in a sample is monitored to make inferences about the population. A causal relationship CAN’T be identified.

Experiment

A study to observe how a controlled variable affects the behavior of another variable. A causal relationship CAN be identified

Confounding Variable

A third factor outside of the Explanatory and Response Variables that influences both and inhibits the ability to draw a causal relationship

Sampling Frame

A list of items that can be randomly selected for a sample

Stratified Sampling

Dividing samples into like-groups(“Strata”) and then collecting simple random samples to observe the specific groups and more accurately represent the population

Cluster Sampling

Dividing populations into heterogenous groups(“Clusters”) and randomly selecting a few clusters to observe.

1 in k Systematic Sample

Predetermined randomized list of items. A value of k is selected so as a random 1 in the first k elements is chosen. Every subsequent kth element is included in the sample

Voluntary Response Sampling

Obtaining samples from purely volunteer-based participation

Extraneous Variable

A variable not being studied but has an effect on the response variable

Directly Control

Way of keeping extraneous variables constant to negate effects on experiment

Random Assignment

The process of randomly placing those in a sample into different groups to ensure even experimental groups to observe the effects of explanatory variables

Replication

Making sure that enough data is recorded for every observation to ensure effective inferences

Principles of Experimental Design

Random Assignment

Blocking

Direct Control

Replication

Control Group

A sample that has no treatments or uses a standard treatment in order to compare the response variable in reaction to the explanatory variable

Experimental Unit

Smallest unit to which a treatment is applied

Overcoverage vs. Undercoverage

Overcoverage has a sample larger than the population while Undercoverage has a sample that doesn’t fully represent the population