Vocabulary of Data Collection

AP Statistics - Unit 2

When a significant number of participants do not return their surveys. This could result in bias.

Nonresponse Variable

Every person or object of interest in a study

Population

Pick a sample and gather data about their past

Retrospective Study

The control treatment used in medical experiments

Placebo

We must ______ aspects of the experiment that we believe will effect response

Control

A sample in which each group of n units has an equal chance of being selected

Simple Random Sample

When you randomly pick a starting point on a list and select every 5th person thereafter

Systemic Sampling

When individuals from a subgroup of the population are not represented

Undercoverage

When both those influencing the results and evaluating the results of an experiment don't know which treatment was applied to the participants

Double Blind

When entire groups, which are representative of the population are chosen randomly for a survey.

Cluster Sampling

A hopefully representative subset of the population

Representative Sampling

A combination of specific levels of the factors in an experiment. Ex: a new medication plus a high level of exercise.

Treatment

In an experiment, you need many subjects in order to assess the variation in response and be confident our results are not just due to chance or other variables.

Replication

Pick a sample and follow them into the future, observing and collecting data about the sample.

Prospective Study

A data value (such as mean) attributed to the population or used as a value to model the population.

Parameter

When the population is subdivided, and random samples are drawn from each group. The groups should each represent a group characteristic which may influence response.

Stratified Sampling

A variable that is used to group participants in an experiment before assigning treatments.

Blocking Variable

When you can't determine which variable is affecting the difference in the outcomes of an experiment, then the variables are ___.

Confounded

Anything in a survey design that influences the response

Response Bias

When the sample is every individual in the population, we call this a _.

Census

A data value (such as mean) calculated from the sample.

Statistic

In this experimental design, you first divide the participants into groups based on a variable or characteristic that you believe will affect the response. Then you randomly assign to subjects from each group to treatments.

Randomized Blocking Design

The individual persons or objects in the population or sample.

Participant, Units, Subjects

The variables that are manipulated in an experiment are called the ___.

Factors

In an experiment, this evens out the effects of variables we cannot control or that we haven't even thought of.

Randomization

The participants assigned to a baseline treatment level (not necessarily no treatment) used for comparison purposes in an experiment are the ___.

Control group

The natural tendency of random samples to differ from each other

Sampling Variability

When either those influencing the results or evaluating the results of an experiment don't know which treatment was applied to the participants.

Single Blind

Conducting a survey when you have no control over who responds. Ex: phoning people in surveys.

Voluntary Response Bias

Polls, questionnaires, and interviews of a sample of the population are examples of ____.

Survey

Generic term for the participants, subject, or objects in an experiment.

Experimental Unit

When an observed difference is too large to be attributed to chance, we say that the difference is __.

Statistically Significant

Manipulate the environment and study the effects on individuals or objects. This is the only way to prove a cause-and-effect relationship between variables.

Experiment

A sample in which the statistics gathered mirror the population. The best way to get this kind of sample is through a design that incorporates randomness.

Representative Sample

When one variable influences another, we say that they have what kind of relationship?

Cause and Effect

In this experimental design, all experimental units have an equal chance of receiving any treatment. We do not group them by any common variable.

Completely Randomized Design

A poor sampling method in which you choose subjects that are easy to find.

Convenience Sampling

The list of individuals representing the population from which a sample is chosen.

Sampling Frame

This type of variable is also called the factor in an experiment.

Explanatory Variable