7- Significance test Flashcards
What is a significance test ?
a statistical procedure for evaluating the plausibility of the null hypothesis.
What is another word for statistically significant ?
It simply means unusual. It low for occuring by chance
What is a null hypothesis ?
a hypothesis about the distribution of scores from which a sample was drawn.
What is the formula for zobs?
m-mew/om
What is z obs ?
A test statistic
What is a test statistic ?
is computed from a sample statistic, such as the sample mean.
We say that a statistic is statistically significant when…
it has a low probability of occurrence under the null hypothesis.
What is a p-value ?
It expresses the probability of a statistic, or one more extreme, occurring by chance when the null hypothesis is true.
When rejecting a null hypothesis we treat is as…
Tough
When a hypothesis is plausible we…
Retain it. It just mean that evidence (zobs) is not sufficient for us to treat it as implausible.
What is the criterion for significance of the p-values ?
less than 0,05 are statistically significant and more than 0,05 are not !
You want your p-value to be … as possible to be significant
smaller
What are directionnal tests ?
make predictions about whether a statistic will be greater or less than a specified parameter.
Directional tests are also called…
One tailed tests
What are non-directionnal tests ?
make no prediction about whether a statistic will be greater or less than a specified parameter. The p-value associated with a test statistic (such as zobs) is the area in two tails of the distribution
What are non-directionnal tests called ?
Two tailed tests
How do you compute the interval for z obs ?
2* P(zbs)
Any zobs outside the interval ±1.96 will be…
statistically significant
Any zobs within the interval ±1.645 will…
not be statistically significant
What is z critical ?
is the z-score that zobs must exceed for us to reject the null hypothesis. By exceed we mean further from 0 than the criterion.
What is H0: ?
symbolic name for the null hypothesis, and the colon (:) is a way of saying, “what follows.”
How is the alternative hypothesis called ?
The research hypothesis !
How do you express the null hypothesis, when two populations are considered ?
H0: mew1 = mew0
or
H0: mew1-mew0=0
What is the symbol to alternative hypothesis ?
H1
