BME100 f2016:Group15 W8AM L3
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Descriptive Stats and Graphs
For the temperature experiment a mean, or average, was taken for both the values derived from the gold standard and the values derived from the spree headband. An average temperature of 96.6 degrees F was returned from the gold standard, while the spree headband gave an average of 95.5 degrees F. Although these values differ by only just over a degree, the temperatures recorded for each individual show no similarities in pattern. While the gold standard goes up, the spree might go down, or just stay at the same value. The mean alone is no indication of the similarity between the two sets of data, which is proved by taking a look at inferential statistics, specifically the fact that the p-value calculated for the temperature experiments was below 0.05.
From the two sets of data, a Pearson's correlation value was taken. The closer the value is to 1 or -1 from 0, the closer these two sets of data are correlated. A Pearson's correlation value of 0.4246 was calculated for the temperature experiments, showing a somewhat weak correlation between the two sets of data. For this data, a graph was also created for these temperature values, placing spree temperature on the x-axis with the gold standard on the y-axis. This graph is a visual representation of the correlation between the spree headband temperatures and the gold standard temperatures.
As with the temperature experiment, a mean was taken for the pulse values derived from the spree headband and the gold standard. The average heart rate for the gold standard was 98.05 beats per minute while the average heart rate taken from the spree headband was 98.94 beats per minute. These values differ less than a beat per minute, but remember that the mean alone is not an indication of similarity. When grouped with the p-value (0.427) however, the mean acts to further support the notion that the two sets of data are similar.
A Pearson's correlation value was also taken for the pulse experiments. As expected based on observed similarities, the Pearson's correlation value derived from the two sets of data is 0.7462. A graph similar to the one created for temperature was created for the pulse data, placing the spree values on the x-axis and the gold standard on the y-axis. Such a high correlation value is indicative of a strong positive correlation between the two sets of data, supported by both similar means and the visual graph. In terms of measuring pulse, the spree headband is shown to be quite accurate.
As both temperature and pulse experiments involved only two groups, the gold standard and the spree group, the chosen test to run was the T-Test. Both T-Tests were ran through the Microsoft Excel program, and a p-value was given for each. P-values allow one to see whether or not two sets of data are similar or different. A P-value less than 0.05 means that the two sets of data are statistically different from one another, while any value higher than 0.05 means that the two sets of data are similar. In order for the spree headband to be effective and accurate, the values for both temperature and pulse should be close to the values derived from the gold standard. Therefore, each p-value should be higher than 0.05.
For the pulse experiment, the p-value received was 0.427. Far larger than 0.05, the 0.427 value showed that the temperatures recorded from the spree product matches or is close to that of the gold standard. On the other hand, the p-value derived from the temperature experiment was 7.02E^-22, virtually 0. This value shows in fact that the temperatures recorded from the spree headband and the gold standard are statistically different. No matter how much the gold standard values differed, the headband generally returned a temperature of 95 degrees Fahrenheit. Merely looking at the data supports this notion that the two experiments were different. The T-tests show that the Spree device had similar heart rate readings to the gold standard, but failed to deliver similar temperature readings.
Design Flaws and Recommendations
While the pulse readings of the Spree may have been statistically similar to the gold standard, the temperature reading were significantly different. According to standard statistical tests, if the Spree device measured up to the gold standard, then the p-value would be great than p>.05, indicating that there 5% or higher chance the Spree measures up to the gold standard.
Temperature showed the most significant difference from the gold standard with a p-value of p<.05, which indicates that there 95% or higher chance that temperature measurements of the Spree device were different from the gold standard. The statistical test of the pulse yielded a p-value of p<.427, which is within the accepted statistical range for this circumstance; however, that still means there is a 57.3% chance the two data sets are different. Therefore, the Spree could still be improved to have more similar readings to the gold standard.
Thus, the Spree is flawed in its function to measure temperature and its ability to measure pulse could be improved. One recommendation would be to design the Spree to be more sensitive to measuring pulse and temperature with more sophisticated probes. Another recommendation would be to make it more aesthetically appealing so that users would be attracted to its function as a wearable.
Experimental Design of Own Device
To test the effectiveness of regenerated vertebral disc, our experimental design will measure the compressibility and malleability of the disc as well as the hydration levels of the vertebral patients over time. In order for a disc to be healthy, it must be able to handle the shock and stresses of the physical body and must be able to maintain its suppleness. Thus, these two factors are the main determinants in a healthy disc.
The compression test will change the pressure applied on the disc and measure the volume that it compresses to. The test will contain three groups: pig's vertebral disc, metal transplant disc, and our regenerated disc. A sample of size 100 of each disc will be tested. 100 is arbitrarily selected as a number we believe is enough to show the effectiveness of our regenerated disc. These three groups are used to give a standard of comparison to measure the shock-absorbency of our disk. In this case, both the pig's vertebral disc as well as the metal transplant will serve as the gold standard. However, our regenerative disc should perform better than both standards since it is the original human vertebral disc. Our test will be an unpaired test and will require a single ANOVA test to determine the p-value because there are three distinct groups.
The hydration test will measure the hydration levels of the vertebral disc in patients over time. The test will contain two groups: patients without degenerative disc disease and patients who recently went underwent a regenerated disc transplant. Because of the large need for vertebral disc patients, we aim to have a sample size of at least 1000 people per group. The gold standard in this test is the hydration levels of the disc in healthy patients. Patients will need to come into the clinic to have their disc hydration levels measured by an MRI once once a month over the course of a year. The time frame of one year was determined arbitrarily as sufficient time to determine that a disc will retain healthy, hydrated state. The test will be unpaired and use a two-paired t-test to determine the p-value.