# What Are Measures and Metrics?

Measures and metrics are data tracking tools that allow you to see the status of various business elements. Choosing the best method for collecting your measures and metrics will depend on what information you are looking to get from them.

The extent, dimensions, quantity, capacity, etc., of something ascertained especially by comparison with a standard: to take the measure of.

## Units of Measurement

A unit of measurement is a definite magnitude of a quantity defined and adopted by convention or law. It acts as the norm for measurement of a particular kind of physical quantity, and it is possible to express any other value of that kind of quantity as a multiple of the measuring unit.

In science, a variety of uniform systems of units have been used, and many continue to be in use today. The most widely used is the International System of Units, which is also called the metric system, and is internationally agreed upon by scientists. The metric system is based on seven base units and 22 coherent derived units.

For convenience, the metric system also uses prefixes that increase or decrease by powers of 10, making it easier to convert between different units. A few non-metric units remain in widespread use, especially in the United States: for example, “gallons” rather than “liters” are used to describe volume at grocery stores and aircraft altitude is reported in nautical miles instead of feet.

## Measurement Theory

The philosophy of measurement encompasses a wide range of conceptual, metaphysical and epistemological issues that have been argued about for centuries. Some of these issues are discipline-specific while others are more general. Measurement theory is concerned with the conditions under which relationships among numbers and other mathematical entities can be used to express relations between real objects.

Mathematical theories of measurement have been developed by a variety of scholars, including operations theorists and conventionalists. Realists, however, have been critical of these theories.

They have interpreted the axioms of measurement as describing properties of concrete objects rather than observable relations between them. As a result, they have asserted that the precise true values of most physical quantities are unknowable unless derived from a chain of comparisons that traces back to primary measurement standards. They have also questioned why convergence among inaccurate measurements should be taken as evidence of truth. Instead, they have argued that the coherence criterion is a more appropriate standard for assessing the quality of measurement outcomes.

## Measurement Instruments

In practice, measurement experts use instruments to compare dimensions of objects with a preset pattern. This is what enables them to come up with the number that logically shows the relationship between the object and the template. Examples of measurement instruments include rulers, flexometers and gauges. Other instruments are used to verify that the result of a measurement falls within certain limits. These are called verifiers.

The signal produced by a measurement instrument can be displayed, recorded or used as input to some other device or system. The dynamic characteristics of the instrument are important for this task.

A good dynamic characteristic is linearity which means that the output reading of the instrument is proportional to the quantity being measured. The speed of response is another critical dynamic characteristic. This is the time from the moment the sensor ‘S’ receives the physical signal until the measurement is indicated on the display. This is normally expressed in terms of a percentage of the full scale reading.

## Measurement Applications

Measurement leads to numbers, which makes it an important part of arithmetic and statistics. It is also central to design and assembly, where it links to geometry. At work, measurement often seems to be more of a science than mathematics. For example, a lab technician might determine the concentration of potassium in water by using a spectrophotometer, which sends light through the liquid and measures the extinction (disappearance) of this light at different wavelengths.

All measurement systems require input conversion devices to convert the desired input to a number, and readout conversion devices to present this number. There are modifying and interfering inputs, which can change the outcome of a desired measurement in unintended ways. A method for correcting these modifying and interfering inputs is necessary in order to make the measurements precise. The most common purposes for which people use measurement at work are quality, monitoring, making something fit and safety. The results of these measurements are often reported as descriptive measures.

# Mass Measurement

Mass is a fundamental property of matter. It determines an object’s resistance to acceleration when net force is applied.

Measuring mass involves comparing an unknown object to objects of known mass. Typically, this is done using balances and scales, but other tools exist. In space, scientists use inertial balances to find an object’s mass.

## Definition

In physics, mass is the quantitative measure of inertia, which is an object’s resistance to change in its speed or position caused by external forces. The greater the mass of an object, the more it weighs.

Nevertheless, in everyday life the terms “mass” and “weight” are frequently used interchangeably. For instance, in retail commerce, items are labeled with a net weight that refers to mass (grams and ounces). The term “weight” is also used to describe the force of gravity on an object.

The most common way to measure mass is using a balance. The unknown mass of a body is contrasted against a known value of mass to obtain the estimation of the unknown mass. This method works in space and places of no gravity as well since changes in gravity affect both masses on the balance equally. One kilogram is the standard unit of measurement for mass. One kilogram is equal to the fixed numerical value of Planck’s constant h, which is defined as 6.62607015 x 1034 joule seconds.

## Units

Units of measurement are used to quantify physical quantities. The units of mass, length and volume are commonly used in the metric system which is the standard measurement system worldwide. These are called the SI (Systeme International d’unités) base units and include the meter, kilogram, second, ampere, kelvin and mole.

The basic metric unit of mass is the gram, which is equal to about one teaspoon of sugar. A kilogram is about 2.2 United States pounds. The basic metric unit of length is the meter, which is about 3 feet long. A liter is slightly larger than a quart.

All metric measurements are based on powers of 10. Each derived unit is 10 times larger than the base unit, which makes converting one metric measurement to another a straightforward process. For example, a liter is equal to the volume of a cube that measures 1cm1cm on each side. This is a very large cube, but for everyday use, the liter is defined to be 1000cm3 or 1dm31dm3. The names of metric units are formed by attaching prefixes to these base units.

## Scales

Scales can be used to measure mass in a variety of settings. For example, a person’s weight can be measured by standing on a digital scale or using Sir Isaac Newton’s second law of motion (force equals mass times acceleration) to determine the force exerted on the person by gravity.

More sophisticated weighing instruments such as analytical balances measure mass by directly comparing an unknown quantity to a known quantity, eliminating the need for assumptions about gravity. However, these instruments are typically not used in the home.

When using a commercial scale at home or work, it is important to press the tare button on the instrument before adding any objects for measurement. This will eliminate the weight of the container from the final measurement and make it more accurate. An evaluation of 233 dial and digital scales from primary care, diabetology and endocrinology clinics as well as fitness and weight loss centers found that about 17% of the scales had a precision error greater than 2.7 kg or about 1 Body Mass Index (BMI) unit [10].

## Methods

Traditionally, mass measurement has been made using a balance. This compares the obscure mass with a known estimation of its weight and determines its value. It works well enough, but changes in gravity influence it and other factors such as temperature, evaporation, vibrations etc. Therefore, a system that measures masses online and independently of these influencing factors is needed.

Modern mass spectrometer software reports accurate mass measurements to four decimal places and sometimes more for masses below 10 mDa. However, rounding errors will occur if the number of measurements is not sufficiently large. Therefore, when reporting results, it is advisable to report them to at least one decimal place (i.e. significant) to reduce the possibility of error due to rounding. Similarly, the root mean square error (RMSE) of an accurate mass measurement will vary inversely with the square root of the number of measurements, and must be carefully calculated. The RMSE will also depend on the strength of the signal, the ionization technique and the background noise level.