probability and significance

• probability 


   How likely something is to happen – can be expressed as a number (0.5) or a percentage (50% chance of tossing coin and getting a head). In terms of statistical tests near 1 means very likely, and near 0 means very unlikely. If the probability of your results being due to chance is low then you accept your hypothesis as your results are statistically significant and vice versa.
• critical value 


  • The value that a test statistic must reach in order for the hypothesis to be accepted.
• observed value 


  • The value that you have obtained from conducting your statistical test
• significance 


  • If the result of a statistical test is significant it is highly unlikely to have occurred by chance
• type 1 error 


  • Is a false positive. It is where you accept the alternative/experimental hypothesis when it is false
• type 2 error 


  • Is a false negative. It is where you accept the null hypothesis when it is false