## How to Determine a p-Value When Testing a Null Hypothesis

A fairly common criticism of the hypothesis-testing approach to statistics is that the null hypothesis will always be false, if you have a big enough sample size. In the chicken-feet example, critics would argue that if you had an infinite sample size, it is impossible that male chickens would have *exactly* the same average foot size as female chickens. Therefore, since you know before doing the experiment that the null hypothesis is false, there's no point in testing it.

Null Hypothesis Research Hypothesis: Researcher’s expectation, prediction; also called hypothesis or alternative hypothesis

Null Hypothesis: No differences, no effects; differences or effects observed are the result of sampling error What you’re doing with statistics… Have a question/topic

Consult literature; create hypothesis (has an accompanying null hypothesis)

Sample a population and measure

Use statistics to estimate probability of your results being true to population; ruling out your null hypothesis to test the (research) hypothesis Significance Testing Test If you set your significance level at .05 and you get the following, significant or not?

## Hypothesis testing is vital to test patient outcomes.

The probability that was calculated above, 0.030, is the probability of getting 17 or fewer males out of 48. It would be significant, using the conventional *P**P*=0.03 value found by adding the probabilities of getting 17 or fewer males. This is called a one-tailed probability, because you are adding the probabilities in only one tail of the distribution shown in the figure. However, if your null hypothesis is "The proportion of males is 0.5", then your alternative hypothesis is "The proportion of males is different from 0.5." In that case, you should add the probability of getting 17 or fewer females to the probability of getting 17 or fewer males. This is called a two-tailed probability. If you do that with the chicken result, you get *P*=0.06, which is not quite significant.

## Null Hypothesis | Definition of Null Hypothesis by …

*State what will happen if the hypothesis doesn’t come true.* If the recovery time isn’t greater than 8.2 weeks, there are only two possibilities, that the recovery time is equal to 8.2 weeks or less than 8.2 weeks.

## Explainer: what is a null hypothesis? - The Conversation

When you about a , you can use your test statistic to decide whether to reject the null hypothesis, H_{0}. You make this decision by coming up with a number, called a -value.

## Statistical hypothesis testing - Wikipedia

**Example Problem**: A researcher thinks that if knee surgery patients go to physical therapy twice a week (instead of 3 times), their recovery period will be longer. recovery times for knee surgery patients is 8.2 weeks. * *

*Figure out the hypothesis from the problem*. The hypothesis is usually hidden in a word problem, and is sometimes a statement of what you expect to happen in the experiment. The hypothesis in the above question is “I expect the average recovery period to be greater than 8.2 weeks.”

## 5 Differences between Null and Alternative Hypothesis …

*Compare your to α*. Support or reject null hypothesis? If the is less, reject the null hypothesis. If the P-value is more, keep the null hypothesis.

0.003