Let’s focus on the solid line in Figure 5.4. The goal of a linear regression is to find the mathematical model, in this case a straight-line, that best explains the data. : Illustration showing three data points and two possible straight-lines that might explain the data. How do we decide how well these straight-lines fit the data, and how do we determine the best straight-line? Figure 5.4.2 , which shows three data points and two possible straight-lines that might reasonably explain the data. To understand the logic of a linear regression consider the example shown in Figure 5.4.2 In such circumstances the first assumption is usually reasonable. When we prepare a calibration curve, however, it is not unusual to find that the uncertainty in the signal, S std, is significantly larger than the uncertainty in the analyte’s concentration, C std. In particular the first assumption always is suspect because there certainly is some indeterminate error in the measurement of x. The validity of the two remaining assumptions is less obvious and you should evaluate them before you accept the results of a linear regression. The second assumption generally is true because of the central limit theorem, which we considered in Chapter 4. For this reason the result is considered an unweighted linear regression. that the indeterminate errors in y are independent of the value of xīecause we assume that the indeterminate errors are the same for all standards, each standard contributes equally in our estimate of the slope and the y-intercept.that indeterminate errors that affect y are normally distributed.that the difference between our experimental data and the calculated regression line is the result of indeterminate errors that affect y.The CE Marking identifies this product as complying with all relevantMakes three assumptions: Slowly or go blank in temperatures outside this rangeģ.66 x 8.48 x 2.29 cm (1.44 x 3.34 x 0.9 in.) LCD is visible from 0° to 50☌ (32° to 122☏) the LCD may react One 3V CR2032 lithium battery and USB cableġ year, typical with logging rate of 1 minute and sampling interval of ☑ minute per month at 25☌ (77☏), see Plot B in User Manual When memory full, push button, or date & time Immediate, push button, date & time, or next interval Launch/Readout: 0° to 50☌ (32° to 122☏) per USB specificationġ second to 18 hours, 12 minutes, 15 secondsįixed interval (normal), burst, or statistics Hysteresis at 25☌ (77☏) below 10% and above 90% ±5% typicalġ0 seconds to 90% in airflow of 1 m/s (2.2 mph) ☒.5% from 10% to 90% typical to a maximum of ☓.5% including (Note: A USB-A to USB-B mini cable is included w/HOBOware Pro CD or USB software purchase). Requires HOBOware software and a USB cable. User-replaceable relative humidity sensor.This compact data logger has a built-in LCD screen to monitor the current temperature, relative humidity, logging status, battery use, and memory consumption in between readouts. The logger can also calculate minimum, maximum, average, and standard deviation statistics. Or, you can set up burst logging in which the logger records data at a different interval during certain conditions. This logger is ideal for monitoring occupant comfort in office buildings, tracking food storage conditions in warehouses, logging temperature trends in server rooms, and measuring humidity levels in museums. Using HOBOware®, you can easily configure the logger alarm to trip for specific high or low sensor readings. Then you add up all those values for all data points, and, in the case of a fit with two parameters such as a linear fit, divide by the number of points minus two. FlexLogger is application software that helps you build flexible, scalable data-logging systems with NI data acquisition hardware, no programming required. With integrated sensors, measures and records temperature and relative humidity (within 2.5% accuracy) in indoor environments. For every data point, you take the distance vertically from the point to the corresponding y value on the curve fit (the error), and square the value. FlexLogger is application software for quick sensor configuration and data logging of mixed signals to verify electromechanical systems, all without programming. Accurately Measure Temperature & Humidity
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