Statistics Year 1 Unit 7 Flashcards
A hypothesis test is …
a statement made about the value of a population parameter, which you can test by carrying out an experiment or taking a sample from the population
A test statistic is …
The result of the experiment or the statistic that is calculated from the sample
What is the null hypothesis?
H0, the hypothesis you assume to be correct
What is the alternative hypothesis?
H1, tells you about the parameter if your assumption is shown to be wrong
One tailed tests are …
When your alternative hypothesis is in the form > or
Two tailed tests are …
When your alternative hypothesis is in the form =/=
When do you reject the null hypothesis?
You assume it is correct, then if the likelihood is less than a given threshold, called the significance level, then you reject the null hypothesis
A critical region is
a region of probability distribution which, if the test statistic falls within it, would cause you to reject the null hypothesis
The critical value is
The first value to fall inside the critical region
The acceptance region is
The region where we accept the null hypothesis
The actual significance level is
the probability of incorrectly rejecting the null hypothesis
How many critical regions are there in a two tailed test?
two, one at each end of the distribution
If you have to carry out a one tailed hypothesis test you need to:
.Formulae a model for the test statistic
.Identify suitable null and alternative hypothesis
.Calculate the probability of the test statistic taking the observed value, assuming the null hypothesis is true
.Compare this to the significance level
.Write a conclusion in the context of the question
.Alternatively you can find the critical region and see if the observed value of the test statistic lies inside it
For a two tailed test, what must you do to the significance level
halve it
