Chapter 1: STATS 201

Problems with samples

a sample must be representative of the population one that's not representative of the population is biased

outlier

an observation of data that does not fit the rest of the data

Sampling methods (Qualitative)

anything that doesn't have a # associated with it, arranged into categories based on physical traits

Bin

represents a range of data and is used when displaying large data sets. Bins are also called intervals. All bins have the same width.

self-selected samples

responses only by people who choose to respond, such as call-in surveys, are often unreliable

Sampling methods (Cluster)

sampling method where multiple clusters of people are created from a population and have equal opportunities of being chosen

Parameter

A number that is used to represent a characteristic of the population and that generall cannot be determined easily

Statistic

A number that represents the property of intent in the sample

Sampling methods (Convenience)

taken from a group of ppl who are easy to reach "ie: standing @ a grocery store or mall and getting people to answer questions" (mostly biased)

Quantitative Discrete

"How many times"

Variable

A characteristic or measurement that can be determined for each member of a population

Distribution

A listing or function showing all the possible values or intervals of the data and how often they occur

Sample

A subset of the population of interest that we will collect data on

Representative sample

A subset of the population that has the same characteristics and the population of interest

Data

Actual values of the variable

Population

All individuals objects or things whose properties are being studied

Quantitative Continuous

Can't count, just ongoing

Stats

Collecting, organizing, a slay zing, and interpreting data to make decisons

Role of a statistician

Design studies, analyze data, translate data into knowledge and understanding the world around us

Percentile

Divide ordered data into hundredths

inferential stats

Drawing conclusions from data

Sampling methods (Simple random)

Equal chance of being selected

Descriptive stats

Focus on description of data

Probability

Foundation of stats; study of uncertainty

Time series Graph

Given a paired data set, we start with a standard cartesian coordinate system. The horizontal axis is used to plot the date/ time increments and the vertical axis is used to plot the values of the variable that we're measuring.

Probability theory

Help to decide on the size poll

Sampling methods (Stratified)

Probability sampling technique, (dividing entire population and selecting @ random

Terminology

The whole class : population,

Sampling methods (systematic)

chooses in logical way (like every "nth" participant on a list of names) (mostly biased)

undue influences

collecting data or asking questions in a way that influences the response

stem and leaf

divide each observation of data into a stem and leaf

quartile

divide ordered data into quarters

non-response or refusal of subject to participate

the collected responses may no longer be representative of the population. Often, ppl w/ strong positive or negative opinions may answer surveys, which can affect the results

histogram

used to visualize distribution for quantitative variables