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# Data Analysis

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Using the data you have been collecting below, please do the following:

(1) Using Excel, prepare a frequency distribution from the data you've been collecting.
(2) Calculate the standard deviation of your data.
(3) Is this a normal distribution?
(4) What are the implications?
(5) Write a 2 page paper.

DATA

I have gathered quantitative data on the amount of time I spend using the computer on a daily basis. For ten days, I have collected data (number of hours) for a sampling. The procedure that I followed is as follows:

1. Record the time I log on to the computer.
2. Record the time I log off the computer.
3. Tally the total number of hours logged in at each sitting.
4. Sum up all the sitting time totals to get a daily grand total.
5. List the grand totals for each day.

RESULTS

DAY ONE: TIME TOTAL HRS
8AM - 10:34AM 2HR 34 MIN 6.6
1:17PM -3:05PM 1HR 48 MIN
7:45PM - 9:58PM 2HR 13 MIN

DAY TWO:
7:12am - 8:25am 1HR 13 MIN
12:55pm - 2:36PM 1HR 41 MIN 5.2
9:49pm - 12:48am 2HR 59 MIN

DAY THREE:
6:25PM - 10:11PM 3HR 46 MIN 6.6
11:30PM - 2:20PM 2HR 50 MIN

DAY FOUR: TIME TOTAL HRS
5:56PM - 9:37PM 3HR 41 MIN 5.5
11:00PM - 1:49AM 1HR 49 MIN

DAY FIVE:
2:32PM - 7:04PM 4HR 32 MIN 7.2
10:56PM - 1:36AM 2HR 40 MIN

DAY SIX:
6:48PM - 11:35PM 4HR 47 MIN 4.8

DAY SEVEN:
3:40PM - 6:00PM 2HR 20 MIN 2.3

DAY EIGHT:
7:15AM - 11:34AM 4HR 19MIN 7.8
1:55PM - 4:25PM 3HR 30MIN

DAY NINE:
12:24PM - 3:18PM 2HR 54 MIN 7.6
7:00PM - 11:46PM 4HR 46 MIN

DAY TEN: TIME TOTAL HRS
4:29PM - 11:56PM 7HR 27 MIN 7.5

https://brainmass.com/statistics/frequency-distribution/data-analysis-169153

#### Solution Preview

Statistics

Using the data you have been collecting below, please do the following:

Using Excel, prepare a frequency distribution from the data you've been collecting.
Calculate the Standard Deviation of your data.
Is this a normal distribution?
What are the implications?
Write a 2 page paper (could be more if you want).

DATA
I have gathered quantitative data on the amount of time I spend using the computer on a daily basis. For ten days, I have collected data (number of hours) for a sampling. The procedure that I followed is as follows:
1. Record the time I log on to the computer.
2. Record the time I log off the computer.
3. Tally the total number of hours logged in at each sitting.
4. Sum up all the sitting time totals to get a daily grand total.
5. List the grand totals for each day.

RESULTS:

DAY ONE: TIME TOTAL HRS
8AM - 10:34AM 2HR 34 MIN 6.6
1:17PM -3:05PM 1HR 48 MIN
7:45PM - 9:58PM 2HR 13 MIN

DAY TWO:
7:12am - 8:25am 1HR 13 ...

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## BIOSTATISTICS

2.A group of 25 subjects have their diastolic blood pressures measured. The results, in SPSS are:

|-----------|-------|--------|
|N |Valid |25 |
|-------|--------|
| |Missing|0 |
|-----------|-------|--------|
|Median |85.00 |
|-------------------|--------|
|Mode |82.00 |
|-------------------|--------|
|Minimum |55.00 |
|-------------------|--------|
|Maximum |110.00 |
|-----------|-------|--------|
|Percentiles|25 |71.00 |
| |-------|--------|
| |50 |85.00 |
| |-------|--------|
| |75 |98.00 |
|--------|-------|--------|

Don't worry about values exactly at the endpoints of these intervals. Do the calculations roughly.
(1 point each)

a. What percentage of subjects were from 55 to 85?
b. What percentage of subjects were < 85?
c. What percentage of subjects were from 71 to 85?
d. What percentage of subjects were > 71?
e. What percentage of subjects were > 98?
f. Is there one value more common than the rest, and if so, what is it?

3. Assume you have already been give a Z value. This saves you a step. Consider and determine the following probabilities (1 point each).

A. Pr (-1 < Z < 1)
B. Pr (0 < Z < 1)
C. Pr (Z > 1)
D. Pr (-1 < Z < 0)
E. Pr (Z < -1)
F. Pr (Z > -2)
G. Pr (-1 < Z < 2)

4. Suppose the mean systolic blood pressure in a group of individuals is 150 mmHg, with a standard deviation of 15. Assuming SBP follows a normal distribution in this population, compute (1 point each):

A. Pr (135 < value < 165)
B. Pr (value > 165)
C. Pr (value < 135)
D. Pr (138.75 < value < 161.25)

5 Compute the 5th, 50th, and 95th percentiles of SBP from the previous question. (3 points: 1 each).

In questions 6 - 8, use the 1 and 2 SD rules, without the table.

6.In general, what percentage of a Gaussian data set is within 1 SD of the mean? What percentage is within 2 SD's of the mean? (2 points: 1 each)

7.If the mean grade on an exam was 80, SD = 6, where did about 68% of the grades fall? How about 95%? Assume the grades are Gaussian. (2 points).

8.Consider the following data: 1, 1, 2, 2, 4, 5, 6, 9, 40, 200

Use the 68% and 95% rules to test the normality of these data. (2 points).

9.A researcher studying a subtype of lymphocytes obtains a sample mean of 100 per mL, and a standard deviation of 20, with 25 subjects. Within what interval can you be roughly 68% sure the population mean number of these cells per mL lies? How about 95% sure? (2 points)

10.A researcher has a sample of 500 subjects. The mean is 40, median is 20, range 10-100. (2 points each)

a.Could this researcher calculate a useful interval with 95% probability of containing the population mean (using the mean and SEM)? Explain

b.Could the researcher use the mean and SD to usefully estimate where 95% of the individual subject values were? Explain

c)If there were 10 subjects, would your answers to a and b change?

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