# Readers ask: When to reject the null?

## When should we reject the null hypothesis?

Set the significance level,, the probability of making a Type I error to be small — 0.01, 0.05, or 0.10. Compare the P-value to. If the P-value is less than (or equal to), reject the null hypothesis in favor of the alternative hypothesis. If the P-value is greater than, do not reject the null hypothesis.

## How do you know if you reject or fail to reject?

Suppose that you do a hypothesis test. Remember that the decision to reject the null hypothesis (H ) or fail to reject it can be based on the p-value and your chosen significance level (also called α). If the p-value is less than or equal to α, you reject H ; if it is greater than α, you fail to reject H .

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## When should you reject a test?

If the absolute value of the t-value is greater than the critical value, you reject the null hypothesis. If the absolute value of the t-value is less than the critical value, you fail to reject the null hypothesis.

## Is it easier to reject the null hypothesis?

Higher values of α make it easier to reject the null hypothesis, so choosing higher values for α can reduce the probability of a Type II error.

## Do you reject null hypothesis p value?

If the pvalue is less than 0.05, we reject the null hypothesis that there’s no difference between the means and conclude that a significant difference does exist. If the pvalue is larger than 0.05, we cannot conclude that a significant difference exists.

## What does reject the null hypothesis mean?

If there is less than a 5% chance of a result as extreme as the sample result if the null hypothesis were true, then the null hypothesis is rejected. When this happens, the result is said to be statistically significant.

## What happens when you fail to reject the null hypothesis?

When we fail to reject the null hypothesis when the null hypothesis is false. The “reality”, or truth, about the null hypothesis is unknown and therefore we do not know if we have made the correct decision or if we committed an error. We can, however, define the likelihood of these events.

## What does p value 0.05 mean?

P > 0.05 is the probability that the null hypothesis is true. A statistically significant test result (P0.05) means that the test hypothesis is false or should be rejected. A P value greater than 0.05 means that no effect was observed.

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## How should you interpret a decision that fails to reject the null hypothesis?

There is enough evidence to reject the claim. e) How should you interpret a decision that fails to reject the null hypothesis? There is not enough evidence to reject the claim.

## How do you reject the null hypothesis for an F test?

When you have found the F value, you can compare it with an f critical value in the table. If your observed value of F is larger than the value in the F table, then you can reject the null hypothesis with 95 percent confidence that the variance between your two populations isn’t due to random chance.

## What is p-value formula?

The pvalue is calculated using the sampling distribution of the test statistic under the null hypothesis, the sample data, and the type of test being done (lower-tailed test, upper-tailed test, or two-sided test). The pvalue for: an upper-tailed test is specified by: pvalue = P(TS ts | H is true) = 1 – cdf(ts)

## Why do we reject the null hypothesis when the p-value is small?

A pvalue less than 0.05 (typically ≤ 0.05) is statistically significant. It indicates strong evidence against the null hypothesis, as there is less than a 5% probability the null is correct (and the results are random). Therefore, we reject the null hypothesis, and accept the alternative hypothesis.

## When we reject the null hypothesis when it is actually false we have committed?

The other two are errors. If we reject a true null hypothesis, we have committed a type I error. If we accept a false null hypothesis, we have made a type II error. Each of these four possibilities has some probability of occurring, and those probabilities are contingent on whether the null hypothesis is true or false.

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## What does a significance level of 0.01 mean?

The lower the significance level, the more the data must diverge from the null hypothesis to be significant. Therefore, the 0.01 level is more conservative than the 0.05 level. The Greek letter alpha (α) is sometimes used to indicate the significance level.

## How do you fix a Type 1 error?

Type I Error.

If the null hypothesis is true, then the probability of making a Type I error is equal to the significance level of the test. To decrease the probability of a Type I error, decrease the significance level. Changing the sample size has no effect on the probability of a Type I error.