Question

1.) **One tailed test or two tailed test?**

You are performing a hypothesis test for the mean sample weight of your fellow Intro to Statistics students. For your null hypothesis , the hypothesized mean weight for the entire campus student body is 165. You have no reason to know for your alternative hypothesis whether the actual mean weight for the entire student campus body is more or less than 165. So you decide to make your alternative hypothesis as not equal to 165.

Which test should you use?

2.) **One tailed test or two tailed test?**

Separate scenario unconnected to the previous example: If
possible, you would like to be able to show a
**difference** between your sample mean and the
hypothesized population mean at the 95% confidence level. If there
were no other factors to consider (although, sadly, there usually
are), which test should you use?

3.) **Type I error or Type II error?**

The mean sample score for your QC statistics students on the last exam was statistically significant at the 80% confidence level compared to the mean score on that exam for the entire campus population. Even so, you decide to change your confidence level from 80% to 95% and perform the test again. In so doing, you are increasing the chance of which type of error?

4.) **Type I error or Type II error?**

This is your alpha level. It describes the actual level of error or risk involved. Which type of error is this?

5.) You want to examine the relationship between the following two variables (with accompanying attributes) as indicated:

**Age (years) Region of
country **

**0-18 Northeast**

**19-34 Midwest**

**35-54 South**

**55+ West**

Which statistical test between the options below would be the
most appropriate, and **why? **You must
explain your answer.

**a) T test**

**b) Pearson’s r**

**c) Chi square**

6.) A sample of 125 campus students who responded to a questionnaire had a mean age of 22.0 and a standard deviation of 5.0. The mean hypothesized population age for all campus students is 25.0.

a) Set up the hypothesis (one sample t test) for these data at the 95% confidence level. Be sure to include the null hypothesis and alternative hypothesis in your response.

b) Compute the t test statistic for these data.

c) Are you able to reject the null hypothesis, or are you unable to reject it?

d) Calculate the confidence interval for the true population mean at the 95% confidence level.

7.) For the identical scenario, now set your confidence level at
**99%.**

a) Are you able to reject the null hypothesis, or are you unable to reject it?

b) Calculate the confidence interval for the true population mean at the 99% confidence level.

Answer #1

1. Here hypothesis is vs

As alternative hypothesis have inequality sign it is two tailed test

2. Here claim is that there is difference between sample mean and the hypothesized population mean.

Hence it is two tailed test

3. Level of significance and Type I error are same

So increasing CI level will increase the chance of type I error

4. Level of significance and Type I error are same.

So Type 1 error

1.) A sample of 125 campus students who responded to a
questionnaire had a mean age of 22.0 and a standard deviation of
5.0. The mean hypothesized population age for all campus students
is 25.0.
a) Set up the hypothesis (one sample t test) for
these data at the 95% confidence level. Be sure to include the null
hypothesis and alternative hypothesis in your response.
b) Compute the t test statistic for these data.
c) Are you able to reject the...

Conduct a test of the null hypothesis that the mean height for
all students in the Census at School database is equal to 155 cm vs
the alternative that the mean Height is greater than 155 cm. Use a
significance level of 0.05.
a. State the null and alternative hypotheses.
Ho: m = 155
Ha: m > 155
b. Provide the Statcrunch output table.
Hypothesis test results:
Variable
Sample Mean
Std. Err.
DF
T-Stat
P-value
Height
159.86
1.7311103
49
2.8074468...

You perform a hypothesis test for a hypothesized population mean
at the 0.01 level of significance. Your null hypothesis for the
two-sided test is that the true population mean is equal to your
hypothesized mean. The two-sided p-value for that test is 0.023.
Based on that p-value... A. you should accept the null hypothesis.
B. the null hypothesis cannot be correct. C. you should reject the
null hypothesis. D. you should fail to reject the null
hypothesis.

You calculate a one-tailed z-test and find that for your study,
z = 1.40, p > .05.
A. What is the proportion of the curve that is in the critical
region?
B. Is this a Type I or Type II error?
C. Do you reject or fail to reject the null hypothesis?
D. What is the confidence interval?
For a normal distribution with a population mean μ of 80 and a
population standard deviation (σ) of 50, find each probability...

1. You have a two-tailed test. The t critical value is 2.36 and
the test statistic is 3.11. Assume the null hypothesis is true. The
result is (a) Type I error (b) Type II error (c) Correct
decision
2. You have a right-tailed test. The t critical value is 1.74
and the test statistic is 1.46. Assume the null hypothesis is true.
The result is (a)Type I error (b) Type II error (c) Correct
decision
3. You have a right-tailed...

If your critical value is 1.7 then you are running a:
left tailed test
two tailed test
unable to determine from this information
right tailed test
If your critical value is 1.7 and the test statistic is 0.7 you
would:
fail to reject the Ho
reject the Ho
unable to determine from this information
accept the Ho
If your critical value is 1.7 and the test statistic is 0.7 you
would be:
unable to show that the average is less...

If your critical value is ±±1.6 then you are running a:
right tailed test
two tailed test
unable to determine from this information
left tailed test
If your critical value is ±±1.6 and the test statistic is 3.9 you
would:
accept the Ho
unable to determine from this information
fail to reject the Ho
reject the Ho
If your critical value is ±±1.6 and the test statistic is 3.9 you
would be:
able to show that the average was greater...

Is there a relationship between confidence intervals and
two-tailed hypothesis tests? Let c be the level of
confidence used to construct a confidence interval from sample
data. Let α be the level of significance for a two-tailed
hypothesis test. The following statement applies to hypothesis
tests of the mean.
For a two-tailed hypothesis test with level of significance
α and null hypothesis H0: μ =
k, we reject H0 whenever
k falls outside the c = 1 – α
confidence...

describe the null hypothesis and alternate hypothesis and say
whether the hypothesis test is two-tailed, left-tailed, or
right-tailed, then conduct the test and state the proper
conclusion. You must show the details of your calculations.
Specific Electric Company makes a circuit that is advertised to
initiate an alarm if the power supplied to a machine reaches 100
volts. A random sample of 250 switches is tested and the mean
voltage at which the alarm occurs is 98 volts with a...

Is there a relationship between confidence intervals and
two-tailed hypothesis tests? Let c be the level of
confidence used to construct a confidence interval from sample
data. Let α be the level of significance for a two-tailed
hypothesis test. The following statement applies to hypothesis
tests of the mean.
For a two-tailed hypothesis test with level of significance
α and null hypothesis H0: μ =
k, we reject H0 whenever
k falls outside the c = 1 − α
confidence...

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