measurement

Knowledge

2022

We explain what measurement is, how it is done, its instruments, types and units. Also, what mistakes can be made.

The measurement assigns numerical values ​​to one or more objects.

What is measurement?

Measurement is the process by which the measure of one object or item is compared with the measure of another. For this, different numerical values ​​or dimensions must be assigned using different tools and procedures.

To measure, a chosen pattern is compared with another object or phenomenon that has a physical magnitude equal to this in order to calculate how many times the pattern is contained in that particular magnitude. However, this action, which seems so simple to calculate, becomes difficult when what you want to measure and express numerically is intangible or even evanescent.

See also:To size

How should the measurement process be?

The measurement process seeks to distinguish objects, phenomena or cases to classify them. Eastprocess responds to certain requirements and principles:

  • It must be valid. There must be ways to demonstrate how the measurement is done.
  • It must be reliable. The measurement must be applied in several cases and must always provide the same - or similar - results.
  • It must be precise. It must have minimal errors, for that sensitive and faithful measuring tools and instruments must be used.

How to measure accurately?

There are certain provisions to improve the results of a measurement:

  • Use the correct tools for the type of measurement and ensure that they are in good condition.
  • Reduce errors that may occur when handling the measuring instrument, as well as systematic errors.
  • Repeat the measurement as many times as possible and take an average of the results obtained.
  • Reduce all causes of the external environment that may affect the measurement.

Measurement types

  • Direct measurement. A measuring instrument is used that compares the variable to be measured with a certain standard. In this type of measurement, two objects that have the same characteristic are compared. For example: thelength of an object comparing it with the length established in a caliper; the frequency of an object is measured with the frequency of a strobe.
  • Indirect measurement. The desired measurement is obtained by calculating one or more different quantities that were obtained by direct measurement. This is because measurements between variables cannot always be calculated directly, either due to their size, nature or other factors. For example: knowing the acceleration of the gravity.
  • Reproducible measurement. The same result is always obtained if it is possible to carry out comparisons between the same variable and the measuring device used. For example: if the same side of a bed is measured several times, the results will always be the same.

Measurement tools

Each quantity can be measured with various instruments.

Measuring instruments are the tools used to measure an object or item. There are several types of instruments that are classified according to what they measure:

  • Instruments to measure weather. Clock, stopwatch, timer.
  • Instruments to measure weight. Scale, balance, dynamometer, barometer.
  • Instruments to measure length. Ruler, tape measure, EDM, caliper.
  • Instruments to measure temperature. Thermometer, pyrometer, thermohygrograph.
  • Instruments to measure electric current. Ammeter, multimeter, galvanometer.

Measurement units

Units of measurement are standard quantities that are used as a standard to know the measure of objects and elements. The number obtained in any measurement is the result of comparing the object or element and the established unit of measurement.

The International System of Units Recognizes seven basic units of measure: kilogram, meter, ampere, kelvin, second, candela and mole. These units are used in most countries of the world and represent respectively: weight, length, intensity of electric current, temperature, weather, light intensity and amount of substance.

Measurement error

The results obtained in a measurement are not always exact, since different types of errors can occur:

  • Systematic errors. They occur in the same way every time a certain measurement is made due to a fault in the measuring instrument or an error in the measurement. method used. They are errors that are attributed to a physical law so their causes can be determined and corrected.
  • Random errors. They occur inevitably and occur due to changes in the physical environment in which the measurement is made or failures in the operator. They are errors that are not attributed to a physical law, so they cannot be eliminated.

Measurement in chemistry

The chemistry is the science who studies composition and structure of the matter. Matter has certain measurable characteristics such as weight, the mass and temperature, and there are various instruments that are used to measure these properties. Among the most representative are:

  • Balance. Object used to measure the mass of two objects.
  • Thermometer. An instrument used to measure the temperature of a substance.
  • Test tube. Graduated cylinder used to measure volumes.
  • Pipette.Graduated instrument used to measure volumes of liquids.
  • Beaker. Cylindrical container that is used in chemical laboratories and measures the volume of a liquid.
  • Refractometer. Instrument used to measure the density of a substance.
  • Calorimeter. An instrument used to measure the temperature of a substance or body.
  • Erlenmeyer flask. Glass instrument used in the chemical laboratory to measure the volume of a substance.

Measurement in statistics

Statistics is the science that collects and analyzes data that are compared to each other from a series of scales measurement that serve as a reference. There are four types of measurement scales that vary according to the characteristics of the data to be compared.

  • Nominal scale. Qualitative measurement scale that classifies variables into groups or categories and identifies them with a name, symbol or number chosen by the researcher.
  • Ordinal scale. Measurement scale that classifies variables in groups or categories and identifies them with a name, symbol or number that hierarchizes them.
  • Interval scale. Numerical measurement scale that measures the real and numerical difference between two variables. In this type of scale, 0 does not mean the absence of value, but rather it is arranged arbitrarily somewhere on the scale. For example: temperature.
  • Ratio scale. Numerical measurement scale that measures the real and numerical difference between two variables. In this type of scale, 0 represents the absence of measurement. For example: weight.
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