Question

Rerun your inferential analysis using an alpha of 0.05. DO NOT re-write all eight hypothesis testing steps, but tell me if your overall results are different using an alpha of 0.05 (vs. 0.01). If there is a difference, explain why.

Answer 1

We used level of significance for testing of hypothesis.

It is a measure of the strength of the evidence that must be present

in your sample before you will reject the null hypothesis and

conclude that the effect is statistically significant.

The researcher determines the significance level before conducting the experiment.

The significance level is the probability of rejecting the null hypothesis when it is true.

For example, a significance level of 0.05 indicates a 5% risk of

concluding that a difference exists when there is no actual difference.

Lower significance levels indicate that you require stronger evidence

before you will reject the null hypothesis.

1) We have to used 5% level of significance for testing that is = 0.05

We have 95 % confident about null hypothesis is accept but 5% not confident to

our null hypothsis is fail to accept.

2) We have to used 1% level of significance for testing that is = 0.01

We have 99 % confident about null hypothesis is accept but 1% not confident to

our null hypothsis is fail to accept.

And our statistical probability table of critical values are made using different level of

significance with diffrent degrees of freedom.

So, If we can change our level of significance the table or critical values are also changed.

This table or critical values are used to comparing test statistic and decide whether our null hypothesis is accept

or not. also we used the table or critical values are used to computing Confidence intervals.

The critical values are different for different distribution are used.

For example.

1) For normal distribution, it is symmetric

If we used = 0.05

probability curve = 0.025(left tail) + 0.95 + 0.025(right tail)

we need left tailed value of Z then we used the command =NORMSINV(probability) in Excel

Here probability = 0.025 , we used =NORMSINV(0.025) then press Enter gives value

Z= -1.95996 = -1.96 (round two decimal)

Similarly, we need right tailed value of Z then we used the command =NORMSINV(probability)

here probability = 0.025+ 0.95 = 0.975, we used =NORMSINV(0.975) then press Enter gives value

Z= 1.95996 = 1.96 (round two decimal)

2) When we used   = 0.01

probability curve = 0.005(left tail) + 0.99 + 0.005(right tail)

The critical values of Z are as belows

=NORMSINV(0.005) = Z = -2.52583 = -2.58 (left tail)

=NORMSINV(0.995) = Z = 2.57583 = 2.58 (right tail)