probability and significance

• null hypotheses state there is no difference between groups, therefore any differences observed would be due to chance alone
• hypotheses are testable predictions that can be falsified or supported by evidence
• alternative hypothesis states that the null hypothesis is false, meaning there are significant differences between conditions
• a hypothesis is an educated guess about the relationship between two variables
• a one-tailed test predicts which direction the results will go in (either higher or lower) so only needs to find evidence on one side of the distribution
• .05 is the standard level of statistical significance used in psychological research