Correlations - Probability Formulas : All formulas

1 | This is a static webpage to show what this spreadsheet is | ||||
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2 | Critical values for r | designed to do. You can download an editable Excel version | |||

3 | of this spreadsheet by clicking on the link below: | ||||

4 | N (Enter this value) | 40 | tinyurl.com/corr-prob-xls | ||

5 | p < .10 | 0.264 | |||

6 | p < .05 | 0.312 | This spreadsheet will allow you to calculate the critical values | ||

7 | p < .01 | 0.400 | for the correlation coefficient at several levels of p. Just enter | ||

8 | p < .001 | 0.494 | the sample size in the yellow cell marked N and the critical | ||

9 | values will update automatically. | ||||

10 | Inferential tests for r | ||||

11 | In addition, it will calculate p, the level of statistical significance, | ||||

12 | N (Enter this value) | 40 | and several confidence intervals (from 50% to 99.9%) for r | ||

13 | r (Enter this value) | 0.312 | if you just enter the N and the value of r in the blue boxes. | ||

14 | |||||

15 | Null hypothesis test | p | p(rep) | p(rep) is the probability of a statistically significant result if the study were replicated. | |

16 | 0.050 | 0.88 | Certain journals now require this statistic. Generally, you want this one to be high. | ||

17 | |||||

18 | Confidence intervals for r | The rows highlighted in green are commonly used values: | |||

19 | Confidence Level | Low Limit | High Limit | (a) the critical value for a hypothesis test at the .05 level of significance; | |

20 | 50% CI | 0.209 | 0.408 | (b) the observed level of significance for a hypothesis test; and | |

21 | 66.6% CI | 0.162 | 0.448 | (c) the 95% confidence interval (which corresponds to the .05 | |

22 | 75% CI | 0.133 | 0.471 | level of statistical significance) | |

23 | 80% CI | 0.112 | 0.488 | ||

24 | 90% CI | 0.052 | 0.532 | It should be noted that these statistics are based on the Fisher r-to-z | |

25 | 95% CI | 0.001 | 0.568 | transformation. Also, the confidence intervals are based on the | |

26 | 99% CI | -0.100 | 0.633 | central z-distribution (as opposed to the more appropriate but more | |

27 | 99.9% CI | -0.215 | 0.698 | complex non-central t-distributions). However, this is a very common | |

28 | practice, so go right ahead. |