Topic 1: Statistical analysis in lab investigations

Heart rate in sitting and standing.

1. You have carried out 5 trials for each position. Make sure your data table includes uncertinties for time (values must be written in min:00 sec) since you will use sec in your uncertainty) and for counting heart beats. It should also have a descritpive title.

2. Average (mean) your data sets.

3. Determine the standard deviation for each set of data. Show an outline of how you will determine the SD, or write the equation.
The process is as follows, although you can quickly plug the numbers into your calculator or excel for results. In any case, show your work or the formula you used.

x (bar) = mean
x = data value

f = frequency
n = number of values

E = sum
a. subtract the mean from each value : x - x bar (calculate for both data sets)
b. square the numbers: ( x-x bar) square (this gets rid of negative values)
c. sum (add) the numbers you get in (b)
d. divide this number by total number of values -1: E /n - 1
e. now take the square root of this number and you have the standard deviation (SD)

4. Graph the averages for sitting and standing. Show the error bar for SD on each bar. Write uncertainties and units, as well as descriptive title .
5. What trend do you see? Outline how your SD supports or does not support the trend you see. If the difference between the two means is greater than your standard deviations, you can say that this trend you see is probably significant. However, to say that it is statistically significant, requires a statistical test called a t-test.
Outline how you determined your uncertainties.

6. Write a conclusion that answeres your research question. Outline the biology that supports or does not support your conclusion
(you do not need to write an evaluation).

Using a t-test to determine statistical significance between the means of two sets of data (HRate sitting and standing)
1. Gather the means for HR sitting and standing for each student
2. Insert them into the EXCEL columns
3. Determine the variance for each set of data (the squares of the deviation values, that is, before doing the SD's square root). You can insert fx = variance in the EXCEL fx box.
4. Now bring up the t-test function using a two-tail test, unpaired, and an unequal variance type
5. If the t-test P-value is less than .05 (5% significance), the difference of HR between sitting and standing is significant. ..or you can say that the sitting has a statistically significant effect on heart rate.