4: Introduction to Probability Flashcards
What is probability?
The numerical value measuring the likelihood of an event occurring, measured from 0 to 1.
What is an experiment?
A process that leads to one of the possible outcomes.
What is sample space?
The sample space of an experiment contains all the possible outcomes.
What is an event?
Any subset of outcomes of an experiment
Events are ____ if all possible outcomes are included and they are ____ if they do not share any common outcome.
- Exhaustive
2. Mutually exclusive
What is a subjective probability?
A personal assessment of probabilities without referencing data.
What is empirical probability?
The observed relative frequency with which an event occurs.
A large number of repetitions are required for this to be accurate.
What is classical probability?
Infer probabilities with reasoning. Can be calculated, especially when the outcomes of an experiment are equally likely.
What is the law of large numbers?
The empirical probability will approach the classical probability as you increase the number of experiments.
What is a contingency table?
What is a joint probability table?
Shows the general frequency for two qualitative (categorical) variables.
Example being, age range against brand preference.
A joint probability table is the probability version of the contingency table.
How do you determine whether two events might be independent?
1. Compare conditional probability with it's unconditional probability. Does P(A|B) = P(A).
- Does P(A n B) = P(A)P(B).
If both are not satisfied, the events are dependent, (not independent)
Explain Bayes theorem in reference to prior probability and posterior probability
This is the case of updating probabilities based on new information.
The original probability is called prior probabilities.
On the condition of new information, the conditional probabilities is posterior probability.
If 1% of people are fraudulent and they are detected by a system, the posterior probability of them being detected again has increased.
