Making a Decision about the Hypotheses When a P-value is low, typically less than 5%, we say that the sample statistic is statistically significant. We then reject the null hypothesis that the population parameter is equal to a specific value, and we support the alternative hypothesis. We decide that the observed sample statistic is not due to chance alone, and instead reflects the population parameter. Note: If a P-value other than 5% is going to be used as a cutoff, this value must be chosen before the hypothesis test is performed, to prevent confirmation bias. A P-value of 5% is typically used to ensure we are at least 95% certain before we reject the null hypothesis. For example, consider a jury trial: Would you want to convict someone, if you weren't at least 95% certain they were guilty? Consider a drug safety study. Would you want to provide a new drug to the public if you weren't at least 95% certain it was safe enough to use? (10) Is the observed sample proportion of 0.62 statistically significant? Explain. (11) (a) What should we decide about the null and alternative hypotheses? (b) What can we state about the proportion of all students at the college who have concerns that climate change will personally impact themselves or a family member? (12) Can we be 100% certain about our decision from Question 11