# Data Analysis

The study is to find out if the analysis of the data supports a smoking ban or not. I have conducted a Mann Whitney, and N-Par test and discovered that the data is skewed. I need to explain what the results mean in a discussion section, and am unsure because the data is a little random. Can you help?

column a = id of bar/pub

column b = levels of particles in bar.

column c = levels of uvpm (a measure of amount of tobacco smoke in the air) in the pubs/bars.

column d = levels of nicotine in pubs/bars.

column e = ventilation system (yes-fan ect.) (no= natural ventilation).

column f = smoking/non smoking.

1. = smoking area

2. = non-smoking area.

PLEASE SEE ATTACHMENTS

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#### Solution Preview

Smoking and non-smoking pubs.

Here is a brief summary to clarify the difference between the smoking and non-smoking pubs.

o The spreadsheet presents data on levels of pollutants in pubs/bars.

o The first 57 pubs/bars are smoking throughout.

o The rest of the pubs/bars are classed as "non-smoking". This means that, minimally, a non-smoking room is provided. Only two of them are non smoking throughout. Unfortunately, the researchers have not identified which two! In the majority of cases (pubs/bars with a non-smoking area), measurement of the pollutants were taken in the non-smoking area.

I hope this clears things up!

The study is to find out if the analysis of the data supports a smoking ban or not. I have conducted a Mann Whitney, and N-Par test and discovered that the data is skewed. I need to explain what the results mean in a discussion section, and am unsure because the data is a little ...

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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