How can we help?

You can also find more resources in our Help Center.

Trial

A single attempt or realization of a random phenomenon

Outcome

Value that is measured or reported from a trial

Sample Space

Collection of all possible outcomes

Law of Large Numbers

The long run probability will approach its theoretical probability

Independence

When the probability of one event occurring has no affect on the probability of a second event occurring

Probability

A number between 0 and 1 that describes the chance of an event occurring

Disjoint

When two events share no common outcomes

Mutually Exclusive

When two events share no common outcomes

Expected Value

The theoretical long-run average value. AKA the mean

Bernoulli Trials

Have 2 outcomes, probability of a success is constant, trials are independent

Geometric Probability Model

Counts the number of Bernoulli trials until the first success

Binomial Probability Model

Counts the number of successes in n trials

Central Limit Theorem

The sampling distribution model of the sample mean and proportion from a random sample is approximately normal for large n regardless of the distribution of the population as long as observations are independent

Standard Error

When we estimate the standard deviation of a sampling distribution using statistics found from the data

Confidence Interval

An interval used for estimating a parameter

Margin of Error

Tells you the "give or take" from a confidence interval

Alpha Level

The "threshold" p-value that determines whether we reject a null hypothesis

Statistically Significant

When the p-value falls below the alpha level

Significance Level

Another name for alpha level

Type I Error

Rejecting a null hypothesis when it is true. (Also called a false positive) usually denoted by α

Type II Error

Failing to reject a null hypothesis when it is falso (Also called a false negative) usually denoted by β

Power

The probability that a hypothesis test will correctly reject a false null