CH 7 DATA FOR DECISIONS

Population

the entire group of individuals about which we WANT information

Sample

a part of the population & refers to the process of choosing a sample from a population

Convenience Sample

a sample of individuals who are selected because they are members of a population who are easy to reach. Usually, such a sample cannot be trusted to be representative of a population (FULL of Bias)

Bias

systematically favors certain outcomes

Why is variance important?

it is used to help predict outcomes

smaller, easier

The ___ the range, the ___ it is to understand

small, stay

If your variance is ___, you will ___ on target

larger, longer

The ___ the spread, the ___ the curve

Voluntary Response Sample

Consists of people who choose themselves by responding to a general appeal.

Why are Voluntary Response Samples considered biased?

Because people with strong opinions are more likely to respond and will therefore be overrepresented in the sample.

Simple random sample

size n; consists of individuals from the population chosen

Table of Random Digits

a list of the digits 0, 1, 2, 3, 4, ,5 ,6 ,7 ,8, 9 with two properties

2 qualities of the table of random digits:

Each entry is ___ likely to be any of the ten digits 0 through 9

These entries are ___ of each other.

equally, independent

Under coverage/discrimination

occurs when some groups in the population are left out of the process of choosing a sample

Nonresponse

when an individual can't be contacted or refuse to participate in a survey

Experiment

The purpose of an ___ is to study whether the treatment causes a change in the response

Confounding

when their effects on the outcome CANNOT be distinguished from each other; not have been intended to be a part of the study.

Statistically significant

an observed effect that is SO large that it would rarely occur by chance

NO

Can you ignore statistical significance?

Observational study

NO manipulation in an experiment

Placebo effect

the tendency of patients to respond favorably to any apparent treatment (even on that is in reality a "fake treatment") because of their expectation about the treatment

Double-blind experiment

experimenter and subject are unaware as to what is going on

Random

a phenomenon or trial is said to be ___ if individual outcomes are uncertain but the long-term of many individual outcomes is predictable

YES

Can you predict a group of people easier than the outcome of an individual?

Probability

the proportion of times in a random phenomenon the outcome would occur in a very long series of repetition; can be expressed as decimals, percentages, or fractions

Event

subset of sample space

Sample Space

a set of all possible outcomes

Independent:

if the occurrence of one event has NO influence on the probability of the occurrence of another event

Dependent

2 events are reliable on each other

Conditional Probability

we write P(A| B) read “Probability of A given B”

Intersection (P and B)

Bayes’ theorem

Conditional

Union

Mutually Exclusive

Independent