Finding the value for rejection region using some kind of table

In summary, to find the cutoff rejection region and the p-value, you can use a Z-table to find the associated Z-value. If your table gives tail areas, look for the area of 0.01 or 0.99, and if it gives cumulative probabilities, look for the area closest to 0.99 or 0.49. The associated Z-value will be 2.326 or 2.236.
  • #1
korr2221
20
0
I'm lost no how to find the cutoff rejection region and which table to use?

This is an example,
Data

n 34
X-bar 10.3
s 3.1

98% Confidence Interval for µ is
10.3 ± 2.33 x 0.5316
= (9.0632 , 11.5368)

Hypothesis
H0: µ ≤ 9
H1: µ > 9

Tests Z-stat = 1.3 = 2.4452
Statistic 0.5316

Significance Level = 0.01

Rejection Region =
Tail = RIGHT
Cutt -Off = Z-alpha = 2.326
Decision = Reject H0

p-value = 0.0072

I understand how they reject H0, but I am lost how they got 2.326. I think it's in the Z-table but I'm not sure, can someone explain to me clearly. It would also help if you can tell me how to find 0.0072 for the p-value.
 
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  • #2
I'm not sure how your Z table is set up - whether it gives only tail areas or cumulative probabilities.

If it gives tail areas (areas to the right of specific Z-values, do this: look through the AREAS for 0.01 - the associated Z-value will be 2.326

If your Z- table gives cumulative probabilities (areas of the form P(Z <=z)), look for the area that is closest to 0.99 (this is 1 - 0.01) - again, the Z-value should be 2.236.

Some tables only give the area between 0 and specified values of Z. If this is the case, look through the areas for the value closest to 0.49 - again, you should find Z = 2.236.
 

1. What is a rejection region?

A rejection region is a range of values that are unlikely to occur if the null hypothesis is true. It is used to determine whether to reject or fail to reject the null hypothesis based on the observed data.

2. How is the value for the rejection region determined?

The value for the rejection region is determined by the significance level, which is typically set at 0.05. This value represents the maximum probability of making a Type I error (rejecting the null hypothesis when it is actually true).

3. What kind of table is used to find the value for the rejection region?

A statistical table, such as a z-table or t-table, is used to find the value for the rejection region. These tables contain critical values based on the significance level and degrees of freedom for the test.

4. How do you use the rejection region to make a decision about the null hypothesis?

If the test statistic falls within the rejection region, it is unlikely to have occurred by chance and the null hypothesis is rejected. If the test statistic falls outside the rejection region, it is likely to have occurred by chance and the null hypothesis is not rejected.

5. Are there any limitations to using a rejection region?

Yes, the use of a rejection region is based on assumptions and can only provide evidence against the null hypothesis, not in favor of it. Additionally, the rejection region is only one part of the hypothesis testing process and should be interpreted in conjunction with other factors, such as effect size and confidence intervals.

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