Calibration Lab Report
Calibration Lab Report
The purpose of the lab that was completed was to determine the validity and reliability of an electronic spirometer, using a water spirometer as a reference.
Calibration is an important tool in determining whether or not an instrument is valid and reliable. The validity of an instrument is the extent to which a procedure accomplishes what it seeks out to accomplish. Validity can be determined by checking an instrument against another similar instrument. From the tests run between the two instruments, Pearson’s correlation coefficient (r) can be determined. This coefficient is a statistic that quantifies the magnitude of the relationship between two separate variables. The coefficient can range from negative 1 to positive 1. If the number is closer to positive one this means that when the variable increases, so does the other one. When the coefficient is closer to negative one this means when the variable increases, the other one does the opposite. Lastly, if the coefficient is closer to zero this means there is no relationship, positive or negative. The coefficient r can be determined from the following equation: r = N(sumXY)(sumY)/ ¡îN(sum x©÷-(sum x)©÷)(N)(sum y©÷-(sum y)©÷). The coefficient r can then be used to determine the shared variance between the two variables. Shared variance can be determined by the following equation: Shared Variance = r©÷*100. If the shared variance is 75% or better, this means there is a high correlation between the two variables. If the shared variance is between 50-75%, this means there is a moderate correlation between the two variables. Finally, if the shared variance is below 25%, this means there is a low correlation. The reliability of a procedure is also very important. The reliability is the ability of an instrument or procedure to reproduce duplicate measurements. The reliability of a procedure is also calculated using Pearson’s coefficient. It turns out that the reliability coefficient is usually higher than the validity coefficient, since with the reliability test you are not comparing two different procedures or instruments, but the same one; and one would expect that if a procedure was repeated using the exact same instruments then the results would be very similar.
Before any instruments were tested the humidity, barometric pressure, and temperature were recorded. The PH2O was determined by using...