Designing Studies [The Practice of Statistics- Chapter 4]

Confidentiality

________ is not the same as anonymity.

Replication

________- Use enough experimental units in each group so that any differences in the effects of the treatment can be distinguished from chance between groups.

Random

________ sampling avoids bias and produces trustworthy estimates of the truth about the population, so inferences about the population can be made.

Control

________- Keep other variables that might affect the response the same for all groups.

Voluntary response samples

________ are also an example of biased sampling.

Nonresponse

________ occurs when an individual chosen for the sample cant be contacted or refuses to participate.

observational study

A(n) ________ observes individuals and measures variables of interest but doesnt attempt to influence the responses.

Bias

________ is not just bad luck in one sample.

response

The ________ to a dummy treatment is called the placebo effect.

Convenience sampling

________ is a form of bias: using a method that favors some outcomes over others.

Random assignment

________- Use chance to assign experimental units to treatments.

sample survey

A(n) ________ aims to gather information about a population without disturbing the population in the process.

experimental units

The ________ are the smallest collection of individuals to which treatments are applied.

idea of replication

The ________ is to use enough experimental units to distinguish a difference in the effects of the treatment from chance variations due to random assignment.

significant association

A statistically ________ in data from a well- designed experiment does imply causation.

Any breach of confidentiality

________ is a serious violation of data ethics.

Undercoverage

________ occurs when some members of the population can not be chosen in a sample.

Lack of realism

________ can limit the ability to apply the conclusions of an experiment to a larger population.

Anonymity

________ means that individuals are anonymous- their names are not known even to the director of the study.

Sample surveys

________ are a type of observational study.

logic of a randomized comparative experiment

The ________ depends on our ability to treat all the subjects the same in every way except for the actual treatments being compared.

Label

________- Give each member of the population a numerical label with the same number of digits.

Observational studies

________ of the effect of an explanatory variable on a response variable often fail because of confounding between the explanatory variable and one or more variable.

voluntary response sample

A(n) ________ consists of people who choose themselves by responding to a general invitation.

sample survey

The population in a(n) ________ can consist of people, animals, or things.

random assignment

In an experiment, ________ means that experimental units are assigned to treatments using a chance process.

Anonymity

________ is rare in statistical studies.

Random

________ sampling involves using a chance process to determine which members of a population are included in the sample.

sample surveys

Well- designed ________ avoid bias in the sampling process.

random assignment

Although ________ should create two groups of students that are roughly equivalent to begin with, we still have to ensure that the only consistent difference between the groups during the experiment is the experimental variable.

Convenience sampling is a form of bias

using a method that favors some outcomes over others

Label

Give each member of the population a numerical label with the same number of digits

Randomize

Read consecutive groups of digits of the appropriate length from left to right across a line in Table D. Ignore any group of digits that wasnt used as a label or that duplicates a label already in the sample

IMPORTANT

Be sure to understand the difference between strata and clusters

Comparison

Use a design that compares two or more treatments

Random assignment

Use chance to assign experimental units to treatments

Control

Keep other variables that might affect the response the same for all groups

Replication

Use enough experimental units in each group so that any differences in the effects of the treatment can be distinguished from chance between groups