For the first part of this lab, the goal is to determine whether there is a correlation between weight and the change in heart rate during exercise. In other words, do heavier people have a greater increase in heart rate when exercising compared to lighter people? To help answer this question, you will collect heart rate data on yourself before and immediately after exercise. [Please note that you should not complete this portion if you are sick or have concerns that you cannot exercise safely. Contact your TA if you will be unable to provide data.] You will need to determine how you will count your heart rate. Options include an activity tracker that contains a heart rate monitor (like a Fitbit or Apple watch), an app on your smartphone that can determine your heart rate, or manual data collection by placing your finger on your neck or wrist and using a watch to track the time. Data collection procedure: Sit comfortably in a chair and relax. Count your heart rate for 30s. Convert to beats per minute and record your baseline heart rate: __________ (bpm). Exercise for about 1 minute to increase your heart rate, by running in place, doing squats or jumping jacks, or walking up and down the stairs. Count your heart rate for 30s immediately after exercising. Convert to beats per minute and record your exercise heart rate: _________ (bpm). Data analysis procedure: Your TA will post a spreadsheet of the class data for you to analyze. The question we are trying to answer is: Is there a correlation between weight and the percent change in heart rate with exercise? To try to answer this question, you will use a statistical test called a Spearman’s Rank Correlation Test. This statistical test will compare the two sets of data and determine if there is a correlation between them, either positive or negative. To carry out a Spearman’s Rank Correlation Test, we must first define the two parameters we want to compare. For this experiment, our parameters are weight and percent change in heart rate. You will need to determine the percent change in heart rate, or how much the heart rate increases with exercise. To calculate the % change in heart rate: [(Exercise heart rate - Baseline heart rate) / Baseline heart rate] * 100 5. Set up a spreadsheet with two columns of data, one for each parameter, as shown below, and fill in with the class data for your section. 6. Now you will rank the values within each column, from smallest to largest. The smallest value in each data column gets a rank of 1, and the rank increases as the values increase. 7. Next, use the =CORREL formula to determine the correlation coefficient. The correlation coefficient (r) will be a value between -1 and +1. A value close to -1 indicates a strong negative or inverse relationship between the two parameters. A value close to +1 indicates a strong positive relationship. A value close to 0 indicates no correlation. To calculate the correlation coefficient, use the following formula and highlight your rank data where appropriate: =CORREL(rank of parameter 1 data set, rank of parameter 2 data set). Then hit enter. The value that appears is your correlation coefficient. What is your correlation coefficient? Does it imply a strong (positive or negative) correlation? 8. Now that you know the correlation coefficient, you need to determine if the correlation between weight and percent change in heart rate is statistically significant. To do so, you will use what is called a critical value table. The table below shows the critical values for the Spearman’s Rank test.