probability

(noun)

The relative likelihood of an event happening.

Related Terms

  • addition rule

Examples of probability in the following topics:

  • Marginal and joint probabilities

    • For instance, a probability based solely on the student variable is a marginal probability:
    • A probability of outcomes for two or more variables or processes is called a joint probability:
    • If a probability is based on a single variable, it is a marginal probability.
    • Verify Table 2.14 represents a probability distribution: events are disjoint, all probabilities are non-negative, and the probabilities sum to 1.24.
    • We can compute marginal probabilities using joint probabilities in simple cases.
  • Misconceptions

    • State why the probability value is not the probability the null hypothesis is false
    • Misconception: The probability value is the probability that the null hypothesis is false.
    • Proper interpretation: The probability value is the probability of a result as extreme or more extreme given that the null hypothesis is true.
    • It is the probability of the data given the null hypothesis.
    • It is not the probability that the null hypothesis is false.
  • Chi-Square Probability Table

  • Probability Distributions for Discrete Random Variables

    • The probability distribution of a discrete random variable $x$ lists the values and their probabilities, where value $x_1$ has probability $p_1$, value $x_2$ has probability $x_2$, and so on.
    • Every probability $p_i$ is a number between 0 and 1, and the sum of all the probabilities is equal to 1.
    • $\sum f(x) = 1$, i.e., adding the probabilities of all disjoint cases, we obtain the probability of the sample space, 1.
    • Sometimes, the discrete probability distribution is referred to as the probability mass function (pmf).
    • The probability mass function has the same purpose as the probability histogram, and displays specific probabilities for each discrete random variable.
  • Continuous Probability Distributions

    • A continuous probability distribution is a probability distribution that has a probability density function.
    • Each of these individual outcomes has probability zero, yet the probability that the outcome will fall into the interval (3 cm, 4 cm) is nonzero.
    • Unlike a probability, a probability density function can take on values greater than one.
    • The standard normal distribution has probability density function:
    • Boxplot and probability density function of a normal distribution $$$N(0, 2)$.
  • Student Learning Outcomes

  • Probability distributions

    • A probability distribution is a table of all disjoint outcomes and their associated probabilities.
    • A probability distribution is a list of the possible outcomes with corresponding probabilities that satisfies three rules:
    • Probability distributions can also be summarized in a bar plot.
    • 2.20: The probabilities of (a) do not sum to 1.
    • The second probability in (b) is negative.
  • Two Types of Random Variables

    • Their probability distribution is given by a probability mass function which directly maps each value of the random variable to a probability.
    • For example, the value of $x_1$ takes on the probability $p_1$, the value of $x_2$ takes on the probability $p_2$, and so on.
    • The probabilities $p_i$ must satisfy two requirements: every probability $p_i$ is a number between 0 and 1, and the sum of all the probabilities is 1.
    • The resulting probability distribution of the random variable can be described by a probability density, where the probability is found by taking the area under the curve.
    • This shows the probability mass function of a discrete probability distribution.
  • Common Discrete Probability Distribution Functions

    • Some of the more common discrete probability functions are binomial, geometric, hypergeometric, and Poisson.
    • A probability distribution function is a pattern.
    • You try to fit a probability problem into a pattern or distribution in order to perform the necessary calculations.
    • These distributions are tools to make solving probability problems easier.
  • Remarks on the Concept of “Probability”

    • Therefore the probability of heads is taken to be 1/2, as is the probability of tails.
    • Of course, wind direction also affects probability.
    • Questions such as "What is the probability that Ms.
    • Such an approach to probability, however, seems to lose the objective content of the idea of chance; probability becomes mere opinion.
    • An event with probability 0 has no chance of occurring; an event of probability 1 is certain to occur.
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