Statistical Power - People.stat.sfu.ca
Statistical Power - People.stat.sfu.ca
Statistical Power - People.stat.sfu.ca
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• If the cost of environmental effect could be great <br />
the consequences of a false negative error (Type II) <br />
may outweigh those from a false positive (Type I) error. !<br />
• Example: <strong>ca</strong>n we harvest timber without adversely <br />
affecting songbird populations?!<br />
• Typi<strong>ca</strong>l Null Hypothesis: timber harvesting has no effect!<br />
Conduct a low power test, fail to reject null.!<br />
Conclusion: no effect !!!<br />
• (Wrong) assumptions:!<br />
Cost of Type I error > cost of Type II error.!<br />
Failure to reject = accept.!<br />
Consequences of Type I and Type II errors
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