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