Ch. 1 : Explore/Understand Data and Graphs Flashcards
What is population?
the collection of ALL data values (usually large, unknown, and impossible to obtain all values)
What is a sample?
a subset of the population and we can measure characteristics
What is a sample size?
number of observations in a sample (n)
Observational units
are ROWS: individual cases about whom (or which) we record some characteristics
Variables
are columns: characteristics of a person or thing that can be assigned a number or a category
Types of Variables
Categorical and Numerical variables
Categorical Variable
aka Qualitative/ names categories and answers questions about how cases fall into these categories. Data values are usually words
Numerical Variable
aka Quantitative/ a measured variable with units that answers questions about the quantity of what is measured. Data Values are numbers
What are frequencies?
(or counts) are a natural way to summarize categorical variables
What are Two-Way Tables?
Tables displays the counts of two categorical variables at a time conditional on each other
What does it mean to establish Causality?
means to show that an outcome is effected by some treatment
Treatment Group?
those who receive the treatment in an experiment
Control Group
those who did NOT receive the treatment in an experiment
What does it mean if two things are Associated?
when an outcome occurs more often with one group than the other (treatment and outcome are _)
What is a confounding variable?
a characteristic other than the treatment that causes both outcomes
Observational Study?
Researchers DON’T assign choices; they simply see them/ “see and study”
-they do not demonstrate a causal relationship
Experiment?
the researcher actively and deliberately manipulates the treatment variable and assigns the subjects to those treatments, generally at random (one treatment variable manipulated and one outcome variable to measure)
-possible to demonstrate a causall relationship
Principles of Experimental Design
Large Sample Size, Controlled and Randomized, Double-Blind, Placebo
Random assignment
helps balance bias (which happens when assignments aren’t r_m and results are influenced in certain direction
