probability + significance Flashcards
(26 cards)
What does statistical significance mean?
It means the researcher can reject the null hypothesis because a difference or correlation is unlikely due to chance.
What is the null hypothesis?
A statement that there is no difference or relationship between variables in an investigation.
What is an alternative hypothesis?
A statement that predicts a difference or relationship between variables.
What is the usual level of significance in psychology?
0.05 or 5%.
What does a p value of less than 0.05 indicate?
There is less than a 5% probability that the results occurred by chance.
What is a critical value?
The cut-off point used to decide whether to accept or reject the null hypothesis.
What is a Type I error?
Incorrectly rejecting a true null hypothesis (false positive).
What is a Type II error?
Failing to reject a false null hypothesis (false negative).
What is probability in statistics?
A measure of the likelihood that a particular event will occur.
What does a significance level represent?
The point at which the researcher is prepared to reject the null hypothesis.
What is meant by a one-tailed test?
A test used for a directional hypothesis.
What is meant by a two-tailed test?
A test used for a non-directional hypothesis.
How does sample size affect critical values?
The number of participants determines which critical value is used.
What is the calculated value?
The number produced by a statistical test, used to determine significance.
How do you use critical value tables?
Compare the calculated value to the critical value to determine significance.
What happens if the calculated value is equal to or greater than the critical value?
The result is statistically significant; the null hypothesis can be rejected.
What is the main risk of using a 5% significance level?
There is a 5% chance of making a Type I error.
Why might a stricter significance level (e.g. 0.01) be used?
To reduce the risk of Type I error, especially in studies with serious consequences.
What is a false positive in hypothesis testing?
A Type I error.
What is a false negative in hypothesis testing?
A Type II error.
What is the role of degrees of freedom in using critical value tables?
They help determine which critical value to use based on sample size.
Why are statistical tests important in research?
They help determine whether findings are due to chance or represent real effects.
What is meant by ‘statistical impossibility’?
A probability of 0.
What is meant by ‘statistical certainty’?
A probability of 1.
