Classification of errors

1. Gross error 
2. Systematic error 

• Instrumental error
• Environmental error
• Observational error  

     3. Random error

Gross errors:

• These errors occurs due to human mistakes in reading instruments and recording and calculating results of measurements
• Impossible to eliminate gross error completely
• Mathematical analysis of gross error is impossible.
  These errors can be avoided by 2 means

1. Immense care should be taken while taking the reading and recording the data
2. Two THREE OR EVEN MORE READING should be taken for the quantity being measured

Systematic error:
 These are mainly due to the short comings of the instruments and the characteristics  of the material used in instruments such as defective or worn parts environmental effects etc.
    A constant uniform deviation of the operation of an instrument is known as systematic error
There are 3 types of systematic error

1. Instrumental error
2. environmental error
3. Observation error

1. Instrumental errors:
   These errors arise due to
   Inherent short coming in the instruments,misuse of the instruments,loading effects of the instruments
   
   Misuse of instruments : A good instrument used in an unintelligent way may give erroneous result
   
    
2. Environmental error:
   These errors are due to condition external to the measuring device
   ex: Effects of pressure, temperature dust,humidity
   
   These errors can be eliminated by the following  measure

• using instruments in controlled condition
• apply suitable correction to instruments reading 
• apply combated correction
• using sophisticated devices

     3.  Observational errors: These errors occurs due to carelessness of operators
Reasons:

• Working scale reading and working reading of data
• Inaccurate estimations of average reading
• In correct conversion of units 
• Tendency to read high or low.
   

    4.Random errors:
            Some errors still result though the systematic and instrumental errors are reduced or atleast accounted for.
The cause of such errors are unknown and hence the errors are called random error

These errors are generally due to the accumulation of large number of small effects.These errors are generally small,Hence these errors are of real concern only when the high degree of accuracy is required.