1- laboratory work determination of errors of measuring instrument the Purpose of the work

Relative error - refers to the ratio of absolute error to real value and is expressed as a percentage (%):

 = [(А_x - А_о )/А_о]∙100 = ( /А_о)∙100%.
Usually, the error of measuring instruments is determined by the error given.
The ratio of the absolute error to the maximum value of the instrument display is called the relative error expressed as a percentage.
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2. 
   According to the order of measurement conditions, errors are divided into:
   

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  Static errors - are errors that do not change in magnitude over time. The static error of a measuring instrument is caused by measuring a constant with this instrument. If the passport of the measuring instrument indicates the marginal error of measurement under static conditions, then this information cannot be applied to the description of accuracy under dynamic conditions.
  
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  Dynamic errors - are errors that are due to changes in the magnitude of the measurement over time. The occurrence of dynamic errors is explained by the inertia of the components in the measuring chain of the measuring instruments. The main reason for this is that changes in the measurement chain are not instantaneous, but occur over a period of time.
  

3. 
   Depending on the cause (condition):
   

• basic;
• additional errors
An error that occurs in instruments used under normal (calibration) conditions is called a fundamental error. Under normal conditions, the temperature can be 20 C  5 C, humidity 65 %  15 %, atmospheric pressure (750  30) millimeter mercury column, Supply voltage can vary from nominal to  2% and so on.
If the instrument is used in an external environment other than this, the resulting error is called an additional error.
IV. According to the essence, description and possibilities of elimination:

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  • Regular errors;
  
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  • Random errors;
  
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  • Divided into gross errors or misstatements.
  

A systematic error is a component of a general error that is generated, maintained, or changed according to a specific pattern during repeated measurements.
We can describe the common error as follows:

Here: m – regular error t – random error q – gross error

The causes of regular errors are different, and based on analysis and inspection, they can be identified and partially or completely eliminated. The main groups of routine errors are:

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  Methodological errors;
  
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  Instrumental errors;
  
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  Subjective errors.
  

The methodological error is due to the fact that the measurement method is not theoretically clear.
An error due to a design defect in a measuring instrument is called an instrument error. For example, incorrect calibration of the instrument scale, incorrect fastening of the moving part, etc.
A subjective error is an error that is the fault of the observer.
The second component of the total error is a random error, which is a random variable error in repeated measurements of the same quantity under the same conditions.
A gross (transient) error or misstatement error can also occur during the measurement process, which is also a series of random variables.
The gross error is mainly due to the error of the operator (observer) or his incorrect recording of the instrument readings, as well as abrupt changes in the conditions of measurement.
Gross error is often not taken into account when processing measurement results.