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.95 or .99

  • Most statisticians use one of two levels: .95 (95%) or .99 (99%) Although any level can be used.
  • If .95 is selected, it means that if our study shows a 95% probability of truly representing the population, then we can safely assume (with 95% confidence) that our results are valid.
  • Or if we are comparing two groups, we can safely say the the differences between the two groups that was found in the sample are accurate 95% of the time.
  • Valid results are often referred to in publications as significant results or significant findings.
  • Confidence Intervals represent the range of scores that fall within our probability (.95 or .99). IOW: There is a 95% chance that the true mean of the population falls within our lower confidence level and our upper confidence level.