Statistics Exam 2, oops Flashcards
Hypothesis Testing
Compares data to what we would expect to see if a specific H0 were true.
Null Hypothesis
Specific statement about a population parameter made for the purposes of argument.
Alternative Hypothesis
Includes all other feasible values for the population parameter besides the value stated in the null hypothesis.
Two-Sided/Tailed Test
The Ha includes parameter values on both sides of the parameter value specified by the H0.
Test Statistic
A number calculated from the data that is used to evaluate how compatible the data are with the result expected under H0.
Null Distribution
Sampling distribution of outcomes for a test statistic under the assumption that the H0 is true.
P-Value
The probability of obtaining the data (or data showing as great or greater difference from H0) if the H0 were true.
Significance Level
Probability used as a criterion for rejecting the H0.
Type I Error
Rejecting a true null hypothesis. Moving alpha to a smaller magnitude can reduce the chance of it happening.
Type II Error
Failing to reject a false null hypothesis. A larger sample size can decrease the chance of it happening.
Power
The probability that a random sample will lead to rejection of a false null hypothesis. A low probability of a TII Error is said to have high power.
Binomial Distribution
Provides the probability distribution for the number of “successes” in a fixed number of independent trials, when the probability of success is the same in each trial.
Binomial Test
Uses data to test whether a population proportion matches a null expectation for the proportion.
Proportional Model
Frequency of occurrence of events is proportional to the number of opportunities.
X2 Goodness-of-Fit Test
Compares frequency data to a probability model stated by the null hypothesis.
X2 Test Statistic
Measures discrepancy between observed frequencies from the data and expected frequencies from the null hypothesis.
Degrees of Freedom
Specifies which X2 distribution to use as the null distribution.
Critical Value
Value of a test statistic that marks the boundary of a specified area in the tail of a sampling distribution under H0.
Poisson Distribution
Describes the number of successes in blocks of time or space, when successes happen independently of each other and occur with equal probability at every instant in time or point in space.
Continency Analysis
Estimates and tests for an association between two or more categorical variables.
Relative Risk
Probability of an undesired outcome in the treatment group divided by the Pr of the same outcome in a control group.
Odds
Pr of success divided by Pr of failure.
Odds Ratio
Odds of success in one group divided by the odds of success in a second group.
Fischer’s Exact Test
Examines the independence of two categorical variables, even with small expected values.
