probability and significance

• null hypothesis:

  states that there is no difference

  other hypothesis possibly stating the difference known as alternative hypothesis

  statistical tests determine which hypothesis is accepted
• level of significance

  usual level is p<0.05 in psychology

  psychologists never 100% certain about a result as not tested with all people in the target population
• one tailed is a directional hypothesis as it suggests the direction of the experiment as based off previous research
• two tailed non directional hypothesis does not suggest the direction of the experiment as it is not based off previous research
• type 1 error:

  null hypothesis rejected and alternative accepted

  null hypothesis should have been accepted and alternative rejected

  known as false positive

  researcher claims to have found a significant difference
• type 2 error:

  null hypothesis accepted and alternative rejected

  null hypothesis should have been rejected and alternative accepted

  known as false negative

  researcher claims that there was no significant difference