Biology 2244A/B Chapter Notes - Chapter 15: Confidence Interval, Effect Size, Type I And Type Ii Errors
25 Dec 2016
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Statistical significance: if the p-value is as small or smaller than , we say data are statistically significant at level . Test of significance: describe degree of evidence provided by sample against null hypotheses. If h0 is common assumption, strong evidence needed. Need strong evidence that new treatment will save lives if it is costly. There is no border between significant and insignificant. Only increasingly strong evidence as p value decreases. P value for one sided test: half the p value for 2 sided test of the same null hypothesis and data. Evidence against h0 is stronger: when the alternative hypothesis is one sided. Evidence based on data and information about direction of deviation. Sidedness determined by the research question and context before data collection. Look at size of effect as well as statistical significnace. X| - = how far data diverge from null hypothesis. Statistical significance: the sample showed an effect larger than would occur by chance.
