The uncertainty (validity and reliability) of three electrothermometers in therapeutic modality research.
BACKGROUND
Data from electrothermometers are used to determine therapeutic modality usage, but the value of experimental results is only as good as the data collected.


OBJECTIVE
To determine the reliability and validity of 3 electrothermometers from 2 manufacturers.


METHODS
A 3 x 4 x 17 factorial with repeated measures on 2 factors. Independent variables were trial (1, 2, 3), thermometer (mercury thermometer, Iso-Thermex calibrated from -50 degrees C to 50 degrees C, Iso-Thermex calibrated from -20 degrees C to 80 degrees C, and Datalogger), and time (17).


METHODS
Human Performance Research Center.


METHODS
Eighteen thermocouples were inserted through the wall of a foamed polystyrene cooler, and 6 were connected to each of the 3 electrothermometers. The cooler was positioned on a stir plate and filled with room-temperature water (18.4 degrees C). A mercury thermometer was immersed into the water bath. Measurements of the water bath were taken every 10 seconds for three 3-minute trials.


METHODS
The temperature variability of 3 electrothermometers was taken from a calibrated mercury thermometer.


RESULTS
The Iso-Thermex electrothermometers did not differ statistically from each other in uncertainty (validity error +/- reliability error = 0.06 degrees C +/- 0.03 degrees C +/- 0.03 degrees C +/- 0.02 degrees C, P < .05), but both differed from the Datalogger (0.64 degrees C +/- 0.20 degrees C, P < .05). The Datalogger temperature was consistently higher than the mercury thermometer temperature.


CONCLUSIONS
The Iso-Thermex electrothermometers were more stable than the Datalogger, and values were within the published uncertainty (+/-0.1 degrees C) when used with PT-6 thermocouples. The Datalogger we used had an uncertainty of measurement greater than that indicated in the user's manual (approximately +/-0.52 degrees C). Uncertainty of +/-0.84 degrees C can significantly influence the interpretation of results when intramuscular temperature changes are usually less than 5 degrees C.
Jutte
Lisa S
LS
Brigham Young University, Provo, UT, USA. lsjutte@bsu.edu
Knight
Kenneth L
KL
Long
Blaine C
BC
Hawkins
Jeremy R
JR
Schulthies
Shane S
SS
Dalley
Ethan B
EB