What does repeatability in analytical instruments mean?
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What is the concept of repeatability in analytical instruments? Does it refer to the range of errors relative to the actual value after multiple experiments, or what does it mean? For some instruments, the value of accuracy is greater than that of repeatability, while for others it is smaller. Why is this? Some instruments indicate a repeatability of 2%/year – does this mean that the error remains within 2% over the course of a year, indicating stability? Some analytical instruments do not indicate precision; they only state linearity. Does this mean the same thing as precision? Take an oxygen analyzer, for example: Accuracy: ±0.75% of the reading or 0.05% in absolute terms, whichever is greater. What does this mean? What is the concept of absolute value? When saying \"take the larger value\", does it refer to taking the larger numerical value or the higher precision?
The performance indicators of online analytical instruments have broad meanings, but can generally be divided into two categories. One category of performance indicators is related to the operating range and working conditions of the instrument. The scope of work mainly refers to the object being measured, the measurement range, etc ； Working conditions include environmental conditions, sample conditions, power and gas supply requirements, as well as the explosion-proof performance and protection rating of the instruments. Another category of performance indicators is related to the instrument’s analysis signal, that is, the instrument’s response value. Such indicators mainly include sensitivity, detection limit, repeatability, accuracy, resolution, stability, linear range, response time, etc. Limit of detection – refers to the minimum amount or concentration of a substance required to generate an analytical signal that confirms the presence of that substance in the sample; it is a fundamental indicator for characterizing and evaluating the detection capability of an analytical instrument. Repeatability – also known as repeatability error. Repeatability error refers to the deviation between multiple analysis results when the operating conditions of the instrument remain unchanged. Precision refers to the degree of agreement among various measurements taken multiple times of the same quantity; it indicates the magnitude of random errors in the measurement process, and is generally represented by the standard deviation. The accuracy of an instrument refers to the degree to which, under certain measurement conditions, the average value of multiple measurements matches the true value; it indicates the instrument’s ability to give readings close to the true value. The accuracy of an instrument is referred to as precision, or simply accuracy. Resolution – also known as resolving power or discerning ability – refers to the capability of an instrument to distinguish between the nearest adjacent measured values. Stability – refers to the ability of an instrument to maintain its metrological properties unchanged under specified operating conditions. The stability of analytical instruments refers mainly to the variation characteristics of their response values over time. Stability can be characterized by noise and drift. Linear range – refers to the maximum linear interval covered by the calibration curve, and is used to indicate the suitability for measuring the content or concentration of the component being analyzed. The wider the linear range of the instrument, the better. Linearity – also known as linearity error or non-linearity error – generally refers to the maximum deviation between the output curve of an instrument and the corresponding straight line, expressed as a percentage of the instrument’s range.
The moderator upstairs is answering outside the topic and suggests deleting the post. . . . . . . . Hahaha
Repeatability refers to the ability to obtain identical data under different environments, operating conditions, and among different observers, hehe
1. Repeatability is stability; it was explained on floor 2； 2. Large: Low zero drift ； Small: Severe zero drift. 3. Repeatability is just that – repeatability. 4. Yes. 5. Since the error shown is large, this value should be used
Then explain it to me. . . . . This is my understanding
Got it; the answer on the fourth floor is still correct.
I can’t remember what the teacher taught us when we were studying; I only recall that it’s a very complex calculation. Once you understand random errors and systematic errors, as well as precision and accuracy, it becomes much easier to grasp this concept in practical work. The precision we often talk about in our work is actually a combined concept of accuracy and exactness. From the perspective of measurement error, accuracy is a comprehensive reflection of both the random and systematic errors of the measured value.