Final Review
• Chapter 17 (Thinking about Chance)
– Understand the meaning of the term “random” within a statistics context
• Random ≠ Haphazard
• A phenomenon is random if individual outcomes are uncertain but there
...
Final Review
• Chapter 17 (Thinking about Chance)
– Understand the meaning of the term “random” within a statistics context
• Random ≠ Haphazard
• A phenomenon is random if individual outcomes are uncertain but there is nonetheless a
regular distribution of outcomes in a large number of repetitions.
Random is the kind of order that emerges only in the long run.
• – Understand what pro The probability of any outcome of a random phenomenon is a
number between 0 and 1 that describes the proportion of times the outcome would occur
in a very long series of repetitions.
• If an outcome has probability = 0, it NEVER occurs
• If an outcome has probability = 1, it ALWAYS happens
Note: Probability is defined only in the ‘long run’ (this is what we mean by ‘a very long series of
repetitions’; more on this later!)
bability refers to
– Know that probabilities range from 0 to 1
– Understand the myths about chance behavior (i.e., what is the myth of the Law of Averages,
and what does that law actually tell us? What is the myth of short-run regularity?)
– Understand what personal probability refers to
• Coming up with a probability based on one’s own opinion or anecdotal evidence.
• Not based on data. Not scientific.
• Examples:
– “I’ve got a 0.9 probability of passing this exam.”
– “I have a 20% chance of finding a parking spot today”
– “My team has a 90% chance of winning because I am wearing red socks”
Chapter 18 (Probability Models)
– What is a probability model?
Event: a collection of outcomes. Example – throwing an even number on a die roll (what are the
outcomes in this event?)
A probability model for a random phenomenon describes all of the possible outcomes and says
how to assign probabilities to any collection of outcomes
• What is the probability of throwing an even number on a roll?
– What are the rules of probability? You should know these rules and how to apply them.
• Any probability is a number between 0 and 1
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