Round 2 Lecture 3 Flashcards
A Parameter
is a summary measure computed to describe a characteristic of the population
A Statistic
is a summary measure computed to describe a characteristic of the sample
A Hypothesis
is a claim about a population parameter
Null Hypothesis (H0)
Opposite of the alternative hypothesis
May or may not be rejected based on empirical evidence
Alternative Hypothesis (Ha)
Generally the hypothesis that the researcher claims
two-sided alternative
we are equally interested in deviations on either side of the null hypothesis value.
one-sided alternative
An alternative hypothesis that focuses on deviations from the null hypothesis value in only one direction
Logic of Hypothesis Test
- We start by assuming that the null hypothesis is true
- Then we look at the data and check if there is enough evidence to reject the null hypothesis.
- This is the logic of jury trials. In court, the null hypothesis is that the defendant is innocent.
- The evidence takes the form of facts that seem to contradict the presumption of innocence.
P-value
is the probability of seeing the observed data (or something even less likely) given the null hypothesis.
statistically significant
We can define a “rare event” arbitrarily by setting a threshold for our P-value. If our P-value falls below that point, we’ll reject the null hypothesis
The threshold is called
an alpha level
The alpha level is also called
the significance level
False positive
The null hypothesis is true, but we mistakenly reject it.
type 1 error
False Negative
The null hypothesis is false, but we fail to reject it.
type 2 error
Hypothesis about dependence between two discrete (categorical) variables:
Use Chi-square test
