Final answer:
The three main sources of variation affecting reliability are random errors, systematic errors, and environmental errors, which impact precision and accuracy, respectively, as well as the conditions under which the measurements are taken.
Step-by-step explanation:
The three sources of variation that may impact reliability in measurements and observations are typically random errors, systematic errors, and environmental errors. Random errors are inconsistencies in measurements that vary unpredictably from one observation to another, affecting the precision of the results. Such errors can often be reduced by taking multiple measurements and averaging the results. Systematic errors, on the other hand, are consistent and repeatable inaccuracies that lead to a difference between the measured average value and the true value, hence impacting the accuracy of the results. They can result from faulty equipment or experimental design. Environmental errors include variations caused by external conditions such as temperature, humidity, or electromagnetic interference that affect the outcome of measurements.
In addition to these, sources like human error, instrumental errors, and observational errors such as measurement variability, natural variability, and induced variability also contribute to the spread of data and uncertainty in measurements. These include the limitations of the measuring device, the skill of the person making the measurement, irregularities in the object being measured, and any other factors specific to the situation that might influence the results.