Without the ability to measure, it would be difficult for scientists to conduct experiments or form theories. Not only is measurement important in science and the chemical industry, it is also essential in farming, engineering, construction, manufacturing, commerce, and numerous other occupations and activities.

SI units are interrelated in such a way that one unit is derived from other units without conversion factors. SI is used in most places around the world, so our use of it allows scientists from disparate regions to use a single standard in communicating scientific data without vocabulary confusion.

International System of Units

international system of units

This page explains the two most common systems of measurement: the metric system, used widely in Europe and most of the rest of the world, and the Imperial or British system, a form of which is now chiefly used in the USA.

Scientists use metric system because if they want to repeat the work of others, it would be easier to do so because all scientists use the metric system. To metric unit used to measure distance would be: meter and kilometer. Lastly, to metric units used to measure the weight of an object would be: grams and kilograms.

Scientists all over the world use the metric system. There’s a very good reason for this—it’s so everyone is doing the measuring the same way, all over the world. Another good reason to use metric is that you don’t have so much to remember—no 12 inches in a foot or 5,280 feet in a mile. It’s all decimal!

Temperature

Scientists use the Celsius scale for two main reason: In the Celsius scale the freezing and boiling points of water are 100 units (or degrees Celsius) apart, freezing point being 0 degrees Celsius and boiling point being set at 100 degrees Celsius. Hence, the Celsius scale is just easier to use.

Celsius, also called centigrade, scale based on 0° for the freezing point of water and 100° for the boiling point of water. Invented in 1742 by the Swedish astronomer Anders Celsius, it is sometimes called the centigrade scale because of the 100-degree interval between the defined points.

In the classical definition, which is standard throughout the physical sciences, measurement is the determination or estimation of ratios of quantities. Quantity and measurement are mutually defined: quantitative attributes are those possible to measure, at least in principle.

Measurements continue to play an important role throughout everybody’s life, for example, during a medical check-up, a sports competition, when building a house, when controlling temperature in appliances, or while cooking.

Measurement is defined as the act of measuring or the size of something. An example of measurement means the use of a ruler to determine the length of a piece of paper. An example of measurement is 15″ by 25″.

The main functional elements of a measurement system are:

• i) Primary sensing element.
• ii) Variable conversion element.
• iii) Variable manipulation element.
• v) Data transmission element.

Each of the four scales (i.e., nominal, ordinal, interval, and ratio) provides a different type of information. Measurement refers to the assignment of numbers in a meaningful way, and understanding measurement scales is important to interpreting the numbers assigned to people, objects, and events.

Nominal, Ordinal, Interval, and Ratio are defined as the four fundamental levels of measurement scales that are used to capture data in the form of surveys and questionnaires, each being a multiple choice question….Summary – Levels of Measurement.

There are four scales of measurement: Nominal, Ordinal, Interval, Ratio.

Since there are exactly 12 possible birth months, it is discrete, and can be categorical. It is qualitative, as it describes an attribute or quality of the subject, namely the birth month.

Discrete variables can be further divided into two categories: binary (or nominal) and ordinal. Age, heart rate, systolic blood pressure, and cardiac output are examples of continuous variables.

For example, income is a variable that can be recorded on an ordinal or a ratio scale: At an ordinal level, you could create 5 income groupings and code the incomes that fall within them from 1–5. At a ratio level, you would record exact numbers for income.

A nominal scale is a scale (of measurement) that uses labels to classify cases (measurements) into classes. One example of a nominal scale could be “sex”. For example, students in a class would fall into two possible classes, male or female. A sample data set is given below left.

Data at the nominal level of measurement are qualitative. No mathematical computations can be carried out.