Research Methods Y2 - Probability and Significance Flashcards
What is probability in statistics?
A measure of the likelihood that a particular event will occur, ranging from a statistical impossibility (0) to a statistical certainty (1).
What is significance in statistics?
A statistical term that tells us how sure we can be that a difference or correlation exists. A significant result means the researcher can reject the null hypothesis.
What is a critical value?
The numerical boundary or cut-off point between acceptance and rejection of the null hypothesis when testing a hypothesis.
What is a Type I error?
The incorrect rejection of a true null hypothesis, also known as a false positive.
What is a Type II error?
The failure to reject a false null hypothesis, also known as a false negative.
What is the null hypothesis?
The null hypothesis states there is “no difference” or “no effect” between conditions or groups. It is the default position that researchers aim to test.
What is the alternative hypothesis?
The alternative hypothesis predicts that there will be a difference or effect between conditions or groups. It is what the researcher aims to support.
What is the conventional level of significance in psychology?
The conventional level of significance in psychology is 0.05 or 5%. This means there is a 5% or less probability that the result occurred by chance.
What does a 5% significance level mean?
It means there is a 5% or less chance that the observed result occurred due to random variation, and the researcher can reject the null hypothesis.
What is a calculated value?
The numerical result obtained from a statistical test, which is compared to the critical value to determine significance.
How is the critical value determined?
The critical value is determined based on the level of significance (e.g., 0.05), the number of participants (N), and the degrees of freedom (df) for the test.
What is the difference between a one-tailed and two-tailed test?
A one-tailed test is used for a directional hypothesis, while a two-tailed test is used for a non-directional hypothesis. Two-tailed tests are more conservative.
What is a Type I error more likely to occur?
A Type I error is more likely if the significance level is too lenient (e.g., 10% instead of 5%), increasing the chance of falsely rejecting the null hypothesis.
When is a Type II error more likely to occur?
A Type II error is more likely if the significance level is too stringent (e.g., 1% instead of 5%), increasing the chance of failing to reject a false null hypothesis.
Why do psychologists use the 5% significance level?
The 5% significance level balances the risk of making Type I and Type II errors, providing a reasonable standard for claiming statistical significance.
