![Z hypothesis test calculator](https://kumkoniak.com/11.jpg)
Set the significance level,, the probability of making a Type I error to be small - 0.01, 0.05, or 0.10. How do you accept or reject the null hypothesis? That's pretty straightforward, right? Below 0.05, significant. If the p-value is larger than 0.05, we cannot conclude that a significant difference exists. If the p-value 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. How do you reject the null hypothesis with p-value? Since -2.83 is to the left of -1.645, it is in the critical region. If it is greater than -1.645, we will fail to reject the null hypothesis and say that the test was not statistically significant. If the z-value is less than -1.645 there we will reject the null hypothesis and accept the alternative hypothesis.
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How do you reject the null hypothesis from Z test? Also, t-tests assume the standard deviation is unknown, while z-tests assume it is known. It can be used to test hypotheses in which the z-test follows a normal distribution.
![z hypothesis test calculator z hypothesis test calculator](http://www.learningaboutelectronics.com/images/Left-tail-hypothesis-testing.png)
A z-test is a statistical test to determine whether two population means are different when the variances are known and the sample size is large.
![Z hypothesis test calculator](https://kumkoniak.com/11.jpg)