Question 2:

What is the difference between point estimation and interval estimation?

What is margin of error?

Why do we need margin of error in statistics?

Hello, I have a question, however, it is regarding a data set and doing calculations on spss. If I copy and paste my data set, it is too large of a message. How else can I get the data set to you so I can actually ask my question? Can I download an attachment to whoever will answer the question?

Dual-energy X-ray absorptiometry (DXA) is a technique for measuring bone health. One of the most common measures is total body bone mineral content (TBBMC). A highly skilled operator is required to take the measurements. Recently, a new DXA machine was purchased by a research lab and two operators were trained to take the measurements. TBBMC for eight subjects was measured by both operators. The units are grams (g). A comparison of the means for the two operators provides a check on the training they received and allows us to determine if one of the operators is producing measurements that are consistently higher than the other. Here are the data:

(a) Take the difference between the TBBMC recorded for Operator 1 and the TBBMC for Operator 2. (Use Operator 1 minus Operator 2. Round your answers to four decimal places.)

Describe the distribution of these differences using words.

The distribution is left skewed.

or

The distribution is Normal.  

or

The sample is too small to make judgments about skewness or symmetry.

or

The distribution is uniform.

or

The distribution is right skewed.

(b) Use a significance test to examine the null hypothesis that the two operators have the same mean. Give the test statistic. (Round your answer to three decimal places.)
t =

Give the degrees of freedom.


Give the P-value. (Round your answer to four decimal places.)


Give your conclusion.

We can reject H₀ based on this sample.

or

We cannot reject H₀ based on this sample.    

(c) The sample here is rather small, so we may not have much power to detect differences of interest. Use a 95% confidence interval to provide a range of differences that are compatible with these data. (Round your answers to four decimal places.)

(d) The eight subjects used for this comparison were not a random sample. In fact, they were friends of the researchers whose ages and weights were similar to the types of people who would be measured with this DXA. Comment on the appropriateness of this procedure for selecting a sample, and discuss any consequences regarding the interpretation of the significance testing and confidence interval results.

The subjects from this sample, test results, and confidence interval are representative of future subjects

or

.The subjects from this sample may be representative of future subjects, but the test results and confidence interval are suspect because this is not a random sample.

A population has a mean of 300 and a standard deviation of 90. Suppose a sample of size 100 is selected and is used to estimate . Use z-table. What is the probability that the sample mean will be within +/- 3 of the population mean (to 4 decimals)? (Round z value in intermediate calculations to 2 decimal places.) What is the probability that the sample mean will be within +/- 19 of the population mean (to 4 decimals)? (Round z value in intermediate calculations to 2 decimal places.)

Q. 1.  Suppose a population was normally distributed with a mean of 10 and a standard deviation of 2. What proportion of the scores is below 12.5?

Q.2. Let’s say that the average IQ of a group of people is 105 with a standard deviation of 15. What is the standardized (or z- score) of someone:

(a)  with an IQ of 93?

(b)  with an IQ of 135?

No handwriting please, or make it clear

thanks

A survey showed that 79​% of adults need correction​ (eyeglasses, contacts,​ surgery, etc.) for their eyesight. If 20 adults are randomly​ selected, find the probability that no more than 1 of them need correction for their eyesight. Is 1 a significantly low number of adults requiring eyesight​ correction? The probability that no more than 1 of the 20 adults require eyesight correction is nothing.

A public accounting firm requires the following activities

for an audit:

1. Draw a network for this project? (Marks 0.5)
2. Make a forward pass and a backward pass to determine ES, LS, EF, and LF? (Marks 0.5)
3. What are the critical path? (Marks 0.5)

Sequence the jobs shown below by using a Gantt chart. Assume that the move time between machines is one hour. Sequence the jobs in priority order 1, 2, 3, 4.

1. Using finite capacity scheduling, draw a Gantt chart for the schedule (Marks 0.5)
2. What is the makespan? (Marks 0.5)
3. How much machine idle time is there? (Marks 0.5)
4. How much idle time (waiting time) is there for each job? (Marks 0.5)
5. When is each job delivered? (Marks 0.5)
6. Which department is the bottleneck? (Marks 0.5)
7. Calculate the machine utilization? (Marks 0.5)

A professor wants to know whether or not there is a difference in comprehension of a lab assignment among students depending on if the instructions are given all in text, or if they are given primarily with visual illustrations. She randomly divides her class into two groups of 15, gives one group instructions in text and the second group instructions with visual illustrations. The following data summarizes the scores the students received on a test given after the lab. Let the populations be normally distributed with a populations standard deviation of 5.32 points for both the text and visual illustrations.

Is there evidence to suggest that a difference exists in the comprehension of the lab based on the test scores? Use α=0.10.

Enter the test statistic - round to 4 decimal places.

Enter the P-Value - round to 4 decimal places.

Can it be concluded that a difference exists in the comprehension of the lab based on the test scores?

Directions: For each of the following studies, state both the null and alternative hypotheses and the decision rule, then work the problem. Look up the critical value of t that would cut off the tails of the distribution. Note that each study specifies the alpha value to use and whether to use a one- or two-tailed test. Decide whether to reject or fail to reject the null and answer the question. Please copy and paste the text into a document and include your answers in bold font.

There is no sample size for the first example. I will take whatever I can get to help solve

1. Sommer (1999) investigated student satisfaction with distance learning. One group of students took Introductory Psychology over the Internet and another group took the course in the usual classroom lecture format. Students rated their satisfaction with the course on a scale from 1 (not at all satisfied) to 9 (extremely satisfied). Sommer found that students in the distance learning condition had an average satisfaction of 4.33, with a standard deviation of 2.94, whereas students in the classroom format reported a mean satisfaction of 6.67 and a standard deviation of 0.82. State your null hypothesis, use α = 0.05 for a nondirectional test, and report your critical value. Is there a difference between the groups?

2. Wilson (1999) studied impulse control in grade-school children. She studied 25 average third-graders and found a failure of impulse control 4.6 times per day, with a standard deviation of 2.1 times per day. Wilson also studied 36 third-graders diagnosed with ADHD and found that they showed failures of impulse control on average 7.2 times per day, with a standard deviation of 3.1. State your null hypothesis, use α = 0.01 for a directional test, and report your critical value. Do third-graders with ADHD have more trouble with impulse control?

Loftus and Palmer study (1974) demonstrated the influence of language on eyewitness memory. Participants watched a film of a car accident and were asked questions about what they saw. One group was asked “About how fast the cars were going when they smashed into each other?” Another group was asked the same question, except the verb was changed to “hit” instead of “smashed into”. The ‘smasher into” group reported significantly higher estimates of speed than the hit group. Suppose a researcher repeats this study with two samples of college students and obtains the following results:

Is there a significantly higher estimated speed for the “smashed into” group? Use a one-tailed test with α = .01.

a) The t-statistic is

b) Your decision is:

c)The estimated Cohen's d is:

d)The critical t value is

An Office of Admissions document claims that 56.1% of UVA undergraduates are female. To test whether this claim is accurate, a random sample of 220 UVA undergraduates was selected. In this sample, 53.6364% were female. Is there sufficient evidence to conclude that the document's claim is false? Carry out a hypothesis test at a 10% significance level.

A. The p-value is

B. Your decision for the hypothesis test:

A. Do Not Reject H1H1.
B. Reject H0H0.
C. Reject H1H1.
D. Do Not Reject H0H0.

Also, can you do the calculations for finding the p-value on TI-83? Thanks!

Isle Royale, an island in Lake Superior, has provided an important study site of wolves and their prey. Of special interest is the study of the number of moose killed by wolves. In the period from 1958 to 1974, there were 296 moose deaths identified as wolf kills. The age distribution of the kills is as follows.

(a) For each age group, compute the probability that a moose in that age group is killed by a wolf. (Round your answers to three decimal places.)

(b) Consider all ages in a class equal to the class midpoint. Find the expected age of a moose killed by a wolf and the standard deviation of the ages. (Round your answers to two decimal places.)

According to the Centres for Disease Control, 15.2% of American adults experience migraine headaches. Stress is a major contributor to the frequency and intensity of headaches. A massage therapist feels that she has a technique that can reduce the frequency and intensity of migraine headaches.

(a) Determine the null and alternative hypotheses that would be used to test the effectiveness of the massage therapists techniques.

(b) A sample of 500 American adults who participated in the massage therapists program results in data that indicate that the null hypothesis should be rejected. Provide a statement that supports the massage therapists program.

(c) Explain what it would mean to make Type I error.

(d) Explain what it would mean to make a Type II error.

Listed below are brain volumes (cm3 ) of twins.

Test the claim at the 5% significance level that the brain volume for the first born is different from the second-born twin.

(a) State the null and alternative hypotheses.

(b) Find the critical value and the test statistic.

(c) Should H0 be rejected at the 5% significance level? Make a conclusion.

(d) Construct a 95% confidence interval for the paired difference of the population means