| INTD 5064/OCCT 5023 - Applied Statistics for Health Care Practitioners | |||||||
| Magnets and Pain Relief Data Set | |||||||
| Magnet Treatment Group | Placebo Group | ||||||
| Subject | Before | After | Subject | Before | After | ||
| AM | 10 | 10 | LL | 8 | 4 | ||
| AA | 10 | 4 | LM | 10 | 7 | ||
| BC | 8 | 7 | MD | 10 | 5 | ||
| BR | 10 | 0 | MN | 10 | 8 | ||
| CM | 10 | 4 | JJ | 9 | 8 | ||
| FW | 10 | 2 | JA | 10 | 6 | ||
| GM | 10 | 5 | CR | 9 | 8 | ||
| GD | 10 | 5 | WT | 10 | 10 | ||
| HB | 9 | 3 | GJ | 10 | 10 | ||
| MG | 10 | 10 | BD | 7 | 6 | ||
| PD | 9 | 2 | EG | 10 | 10 | ||
| RW | 10 | 2 | RB | 8 | 8 | ||
| SF | 10 | 3 | DO | 10 | 10 | ||
| TS | 10 | 4 | DS | 10 | 10 | ||
| WA | 10 | 10 | NP | 10 | 10 | ||
| SH | 8 | 4 | GE | 10 | 10 | ||
| WK | 10 | 3 | DY | 9 | 9 | ||
| MR | 10 | 0 | KU | 10 | 9 | ||
| MS | 8 | 2 | UT | 10 | 10 | ||
| AR | 8 | 7 | AX | 10 | 10 | ||
| TN
INTD 5064 – Applied Statistics for Health Care Practitioners t-test Homework For the items below, download the data set Magnets and Pain Relief Data Set. These data are a subset of data in a study by Vallbona, C., et al. Response of pain to static magnetic fields in postpolio patients: A double blind pilot study. Archives of Physical Medicine and Rehabilitation, (78), 1200-1203. In the original study, the researchers sought to answer the question “Can chronic pain experienced by postpolio patients be relieved by magnetic fields applied directly over an identified pain trigger point?” Subjects in the Treatment Group had a magnetic device applied to the site of pain for 45 minutes. Subjects in the Placebo Group had a non-magnetic device applied for 45 minutes. All subjects reported their pain before and after the experiment using a 0 to 10 scale (0 was the least pain, and 10 was the greatest pain). The data consist of self-report pain scores recorded before and after the experiment. This homework includes three opportunities to calculate obtained t values: 3.c., 5.e., and 7.b. Two of these items (3.c. and 5.e.) are highlighted. Choose one of the highlighted items to complete (3.c. OR 5.e.). All non-highlighted items are required (including 7.b.). What is/are the dependent variable(s) in the study? the independent variable(s)? Include the scales of measurement. Calculate appropriate measures of central tendency and variability for each variable you will need in this assignment, i.e., “before” and/or “after” pain scores for each group. Justify your choices. You may use Excel to calculate measures of central tendency and variability. A link has been provided for support in doing so. However, you may calculate those by hand or with a scientific calculator as well. The researchers anticipated that Magnet Treatment Group pain scores would be lower than Placebo Group pain scores at the end of the study. Write the null hypothesis, in prose and notation. (Pay close attention to the word “lower” in this exercise. Remember that lower scores indicate less pain and, thus, effectiveness of the magnets. What does this suggest for how the hypotheses are stated and for how the t distribution diagram is drawn?) a.Is the null hypothesis stated above one-tailed or two-tailed?Justify your answer. b.What type of test should be used to test the null hypothesis stated?Justify your answer. c.Using the A-B-C-D format, test the null hypothesis. (Use ? = .05) The researchers wanted to know whether there was a difference in average pain levels for the Magnet Treatment Group and the Placebo Group at the beginning of the experiment. Why would it be reasonable and desirable to show that there were no differences? a.Write the null and alternate hypotheses, in prose and notation. b.Is the null hypothesis one-tailed or two-tailed?Justify your answer. c.What conclusions would you draw if the null hypothesis were rejected? d.What type of t test should be used to test the hypothesis?Justify your answer. Murphy, another investigator who had used another type of magnet, obtained patterns of results that resembled Vallbona’s results. After the experiment with 21 subjects, Murphy’s treatment group’s mean pain score was 5.50, and the standard deviation was 2.50. Murphy wished to test whether his “After” mean was greater than Vallbona’s “After” mean. Why would Murphy be interested in conducting this test? What information would this test provide? Without testing any formal hypotheses, what do the data suggest about differences between Murphy’s “After” mean and Valbona’s “After” mean? Justify your answer. Is the null hypothesis suggested above one-tailed or two-tailed? Justify your answer. What type of inferential test should Murphy use to test the hypothesis? Justify your answer. HINT: In this case, Murphy chose to use Vallbona’s mean as a hypothesized value. Using the A-B-C-D format demonstrated in class, test the null hypothesis that you stated in exercise 3d. (Use ? = .05) Think of a research question that would be appropriate for an independent-samples t-test. Share: The research question Hypotheses in prose and notation. The conclusion you would make if the null hypothesis were rejected. Complete a t-test using the data collected during the first week of class (i.e., the question you asked classmates). You can compare groups via gender or major, depending on your hypothesis. For example, as I mentioned, last year an MLS student asked his classmates how many times they had seen Star Wars. He hypothesized that there was a significant difference between MLS and DEHS students, so he compared those two groups. What type of inferential test should you use and why? Using the A-B-C-D format demonstrated in class, test the null hypothesis. (Use ? = .05) |
10 | 4 | PW | 10 | 9 |
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In: Statistics and Probability
Calculate the NPV for the following projects. Round PVF values in intermediate calculation to four decimal places. Round answers to two decimal places. Use a minus sign to indicate a negative NPV.
In: Finance
Suppose that the term structure of interest rates is flat in England and Germany. The GBP interest rate is 4% per annum and the EUR rate is 3% per annum. In a swap agreement, a financial institution pays 9% per annum in GBP and receives 7% per annum in EUR. The exchange rate between the two currencies has changed from 1.1 EUR per GBP to 1.15 EUR per GBP since the swap’s initiation. The principal in British pounds is 20 million GBP. Payments are exchanged every year, with one exchange having just taken place. The swap will last three more years. What is the value of the swap to the financial institution in terms of euros? Assume all interest rates are continuously compounded.
In: Finance
Suppose that the term structure of interest rates is flat in England and Germany. The GBP interest rate is 4% per annum and the EUR rate is 3% per annum. In a swap agreement, a financial institution pays 9% per annum in GBP and receives 7% per annum in EUR. The exchange rate between the two currencies has changed from 1.1 EUR per GBP to 1.15 EUR per GBP since the swap’s initiation. The principal in British pounds is 20 million GBP. Payments are exchanged every year, with one exchange having just taken place. The swap will last three more years. What is the value of the swap to the financial institution in terms of euros? Assume all interest rates are continuously compounded.
In: Finance
3. An experiment was conducted to evaluate the effectiveness of a treatment for tapeworm in the stomachs of sheep. A random sample of 24 worm-infected lambs of approximately the same age and health was randomly divided into two groups. Twelve of the lambs were injected with the drug and the remaining twelve were left untreated. After 6 months, the lambs were slaughtered and the following worm counts were recorded. Assume the counts are approximately normally distributed.
Drug-treatedsheep 18, 43, 28, 50, 16, 32, 13, 35, 38, 33, 6, 7
Untreatedsheep 40, 54, 26, 63, 21, 37, 39, 23, 48, 58, 23, 39
In: Statistics and Probability
An experiment was conducted to evaluate the effectiveness of a treatment for tapeworm in the stomachs of sheep. A random sample of 24 worm-infected lambs of approximately the same age and health was randomly divided into two groups. Twelve of the lambs were injected with the drug and the remaining twelve were left untreated. After 6 months, the lambs were slaughtered and the following worm counts were recorded. Assume the counts are approximately normally distributed.
Drug-treatedsheep 18 43 28 50 16 32 13 35 38 33 6 7
Untreatedsheep 40 54 26 63 21 37 39 23 48 58 23 39
(a) Construct a 98% confidence interval for the difference of the worm count in a lamb.
(b) Please perform a statistical test and see if the drug treatment reduced the mean worm count in a lamb. Use the significance level 0.05.
(c) What are your assumptions that you assumed in part (b)?
In: Statistics and Probability
An experiment was conducted to evaluate the effectiveness of a treatment for tapeworm in the stomachs of sheep. A random sample of 24 worm-infected lambs of approximately the same age and health was randomly divided into two groups. Twelve of the lambs were injected with the drug and the remaining twelve were left untreated. After 6 months, the lambs were slaughtered and the following worm counts were recorded. Assume the counts are approximately normally distributed.
Drug-treated sheep 18, 43, 28, 50, 16, 32, 13, 35, 38, 33, 6, 7
untreated sheep 40, 54, 26, 63, 21, 37, 39, 23, 48, 58, 23, 39
(a) Construct a 98% confidence interval for the difference of the worm count in a lamb.
(b) Please perform a statistical test and see if the drug treatment reduced the mean worm count in a lamb. Use the significance level 0.05.
(c) What are your assumptions that you assumed in part (b)
In: Statistics and Probability
| Sample 1 | Sample 2 |
| 68 | 76 |
| 29 | 38 |
| 52 | 47 |
| 32 | 36 |
| 53 | 59 |
| 35 | 38 |
| 41 | 36 |
| 36 | 24 |
| 52 | 52 |
| 35 | 40 |
| 50 | 44 |
| 75 | 86 |
| 59 | 69 |
| 63 | 77 |
| 49 | 49 |
Use the XLMiner Analysis ToolPak to find descriptive statistics for Sample 1 and Sample 2. Select "Descriptive Statistics" in the ToolPak, place your cursor in the "Input Range" box, and then select the cell range A1 to B16 in the sheet. Next, place your cursor in the Output Range box and then click cell D1 (or just type D1). Finally make sure "Grouped By Columns" is selected and all other check-boxes are selected. Click OK. Your descriptive statistics should now fill the shaded region of D1:G18. Use your output to fill in the blanks below.
Sample 1 Mean: (2 decimals)
Sample 1 Standard Deviation: (2 decimals)
Sample 2 Mean: (2 decimals)
Sample 2 Standard Deviation: (2 decimals)
Use a combination of native Excel functions, constructed formulas, and the XLMiner ToolPak to find covariance and correlation.
In cell J3, find the covariance between Sample 1 and Sample 2 using the COVARIANCE.S function.
(2 decimals)
In cell J5, find the correlation between Sample 1 and Sample 2
using the CORREL function.
(2 decimals)
In cell J7, find the correlation between Sample 1 and Sample 2 algebraically, cov/(sx*sy), by constructing a formula using other cells that are necessary for the calculation.
(2 decimals)
Use the XLMiner Analysis ToolPak to find the correlation between Sample 1 and Sample 2. Place your output in cell I10.
(2 decimals)
Calculate z-scores using a mix of relative and absolute cell references. In cell A22, insert the formula =ROUND((A2-$E$3)/$E$7,2). Next grab the lower-right corner of A22 and drag down to fill in the remaining green cells of A23 to A36. Note how the formula changes by looking in Column D. Changing a cell from a relative reference such as E3 to an absolute reference such as $E$3 means that cell remains "fixed" as you drag. Therefore the formula you entered into A22 takes each data observation such as A2, A3, A4..., subtracts $E$3 and then divides by $E$7. Since the last two cells have absolute references they will not change as you drag. The ROUND function simply rounds the z-score to two digits.
Now find the z-scores for Sample 2 using the same method you learned above by editing the formula to refer to the correct cells for Sample 2. Make sure each z-score is rounded to 2 places.
| Sample 2 z-scores |
|---|
In: Math
Riverbend City online news advertises that it is read longer than the national news. The mean for national news is 8 hours per week. The following sample of the Riverbend City online news readers is: 5, 7, 6, 2, 4, 8, 5, 4, 18, 21, 8, 7, 4, 5, 6.
a. State the nondirectional hypothesis. Riverbend City online does not read for 8 hours
b. State the critical t for a = .05 (two tails).
c. Answer the following: Is the length of viewing for Riverbend City online news significantly different than the population mean? Explain.
d. Calculate the 95% confidence interval with population mean of 8.
**Need help with b, c, d and is a correct?
In: Statistics and Probability
Seasonal affective disorder (SAD) is a type of depression during seasons with less daylight (e.g., winter months). One therapy for SAD is phototherapy, which is increased exposure to light used to improve mood. A researcher tests this therapy by exposing a sample of patients with SAD to different intensities of light (low, medium, high) in a light box, either in the morning or at night (these are the times thought to be most effective for light therapy). All participants rated their mood following this therapy on a scale from 1 (poor mood) to 9 (improved mood). The hypothetical results are given in the following table.
| Light Intensity | ||||
|---|---|---|---|---|
| Low | Medium | High | ||
| Time
of Day |
Morning | 5 | 5 | 7 |
| 6 | 5 | 8 | ||
| 4 | 4 | 6 | ||
| 7 | 7 | 9 | ||
| 5 | 9 | 5 | ||
| 6 | 7 | 8 | ||
| Night | 5 | 6 | 9 | |
| 7 | 8 | 7 | ||
| 6 | 7 | 6 | ||
| 7 | 5 | 7 | ||
| 4 | 9 | 7 | ||
| 3 | 8 | 6 | ||
(a) Complete the F-table and make a decision to retain or reject the null hypothesis for each hypothesis test. (Round your answers to two decimal places. Assume experimentwise alpha equal to 0.05.)
|
Source of Variation |
SS | df | MS | F |
|---|---|---|---|---|
| Time of day | ||||
| Intensity | ||||
| Time
of day × Intensity |
||||
| Error | ||||
| Total |
State the decision for the main effect of the time of day.
Retain the null hypothesis or Reject the null hypothesis.
State the decision for the main effect of intensity.
Retain the null hypothesis or Reject the null hypothesis.
State the decision for the interaction effect.
Retain the null hypothesis or Reject the null hypothesis.
(b) Compute Tukey's HSD to analyze the significant main effect.
The critical value is_________ for each pairwise comparison.
Summarize the results for this test using APA format.
In: Math