Ch. 1:Stats Vocab

Ch. 1:Stats Vocab

Where to begin…Where to begin…• “But where shall I begin?” asked Alice. “Begin

at the beginning,” the King said gravely, “and go on till you come to the end: then stop.”

~ Lewis Carroll, Alice’s Adventures in Wonderland

We study statistics because…• …anecdotal evidence is not

reliable.• … we don’t wish to be lied to.• … spotting trends helps us

make good decisions• Simply, we study statistics

because we want to make sense of the world.

The Three Steps to StatisticsThe Three Steps to Statistics1.1. ThinkThink – Always use your head. Ask yourself

where you are going and why.2.2. ShowShow – Always let people know what you

are doing. This is the mechanics aspect of Statistics. Show your calculations, graphs, and displays of your data.

3.3. TellTell – Always let people know what you learned. Until you’ve explained your results so that someone can understand your conclusion, the jobs not done!

DefinitionsDefinitions

• StatisticsStatistics is the science of collecting, analyzing, and drawing conclusions from data.

• The population of interestpopulation of interest is the entire collection of individuals or objects about which information is desired.

• When you study an entire population, it is called a censuscensus.

• A samplesample is a subset of the population, selected for study in some prescribed manner.

DefinitionsDefinitions• An Individual is the objects described by a set of

data.• A variablevariable is any characteristic whose value may

change from one individual to another. ex: height, hair color, brand of car, GPA

• DataData results from making observations on one or more variables. It is important to remember that data is not just a set of numbers, but a set of numbers with a context.

ex:ex: the numbers {78, 82, 83} have no the numbers {78, 82, 83} have no meaning by themselves, but when told meaning by themselves, but when told that they are students’ test scores, they that they are students’ test scores, they become meaningful. become meaningful.

DefinitionsDefinitions• A variable is categoricalcategorical (or qualitativequalitative) if the

possible responses fall into categories.ex: brand of car, hair color (usually

words)• A variable is numericalnumerical (or quantitativequantitative) if the

possible responses are numerical in nature.ex: height, AP score (usually numbers)

• NOTE: One way to tell the difference is to consider the question: “Would it make sense to find the average of this variable?” If you can, it’s numerical. If you can’t, it’s categorical.

DefinitionsDefinitions

Observational Study: A study that observes individuals and measures variables of interest but does not attempt to influence the responses.

Experiment: A type of study that imposes some treatment on individuals in order to observe their responses.

DefinitionsDefinitions

Population (or population of interest): The group of all people we want to know about.

Sample: The smaller group we take from our population, in order to make conclusions about that larger group.

Example 1: Critics argue that excessive video game play is a major contributor to the increase in obesity all over the world. Some doctors have begun using the Wii

to help stroke victims regain movement in their arms and legs. Patients who find traditional exercise too

boring or too difficult are more motivated to play the Wii games. Doctors had 12 patients play the Wii three

times a week for 6 months, after which the doctors tested the movement in their arms and legs.

Example 1: Critics argue that excessive video game play is a major contributor to the increase in obesity all over the world. Some doctors have begun using the Wii

to help stroke victims regain movement in their arms and legs. Patients who find traditional exercise too

boring or too difficult are more motivated to play the Wii games. Doctors had 12 patients play the Wii three

times a week for 6 months, after which the doctors tested the movement in their arms and legs.

a. What are the individuals being studied?

b. What variable is being measured?

c. Is this variable numerical or categorical? d. Is this an experiment of observational study?

Example 1: Critics argue that excessive video game play is a major contributor to the increase in obesity all over the world. Some doctors have begun using the Wii

to help stroke victims regain movement in their arms and legs. Patients who find traditional exercise too

boring or too difficult are more motivated to play the Wii games. Doctors had 12 patients play the Wii three

times a week for 6 months, after which the doctors tested the movement in their arms and legs.

Example 1: Critics argue that excessive video game play is a major contributor to the increase in obesity all over the world. Some doctors have begun using the Wii

to help stroke victims regain movement in their arms and legs. Patients who find traditional exercise too

boring or too difficult are more motivated to play the Wii games. Doctors had 12 patients play the Wii three

times a week for 6 months, after which the doctors tested the movement in their arms and legs.

Exit Slip:Exit Slip:

On a slip of paper, write down three new things that you learned today and two things that you’ve learned today but already knew.