MEASUREMENTS, ERRORS AND BASIC STATISTICS

• Measurement: A direct or indirect process of determining the extent, size of dimension of a quantity in comparison to a given standard. It consists of several physical operations which renders a numerical value
• Observation: Single, unadjusted determination of a linear or angular value
• Measurement: Entire process of obtaining a desired quantity
• Statistical variation: is an inherent quality of physical properties attributed to observational errors
• No Exact or true measurement is ever possible and the value of a measured quantity is never known.
• Metric system or SI (international System): Official system of measurement; Measurement are based upon the meter
• Sources of Errors:

  Natural Errors

  Instrumental Errors

  Personal Errors
• Natural Errors are caused by variations in the phenomenal of nature such as changes in magnetic declination, temperature, refraction, and the like.
• Instrumental Errors are caused due to imperfection in the instruments used, either from faults in construction of improper adjustments
• Personal errors arise principally from the limitations of the senses of sight, touch and hearing of the observer
• Types of errors

  Mistakes or Blunders

  Systematic or Cumulative Errors

  Random or Accidental Errors
• Mistakes or blunders are actually not errors because they are usually so gross in magnitude compared to the other types of errors
• Systematic or Cumulative errors Caused by Physical and natural conditions that vary in accordance with known mathematical or physical law
• Random or Accidental Errors are produced by irregular causes that are beyond the control of the observer
• Precision degree of refinement and consistency of the performance of an operation used to obtain the result; measure of uniformity or reproducibility of the result
• Accuracy is the degree of conformity with a standard or accepted value; denotes how close a given measurement is to the absolute true value of the quanityt