# Units of measured quantities

In physics a measurement consists of four parts:
1.) The object that is being measured(e.g. a brick)
2.) The quantity of the object (e.g. a bricks mass)
3.) The value of the quantity (e.g. 1.5)
4.) The unit that the value takes (e.g. kilograms).

How do economists see this? Do they see it for example like this:
1.) Firm/Household
2.) Production/Consumption
3.) 10
4.) Apple (or more generally piece)

If they do so, how does one define the quantities? Can one define for example production/consumption as the goods produced by the firm/ consumed by the household?

And if yes, could one say that the value of the quantity refers to the amount of that quantity? E.g. the amount of apples (pieces) produced by the firm/consumed by the household?

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• Not sure what the downvoters' problems were, but I am having a hard time grasping what it is exactly that you are asking. When economists want to measure how many apples a household consumes, they do indeed look at the number of apples that the household has consumed. Usually they would probably go for value or weight of apples, but in every case what you measure depends on what you want to measure. In case this is not what you are asking, can you please clarify your question? 2 days ago

I used to study physics before economics and we learned that measurement consists just of 1) unit of measurement 2) number of units.

In any case, for measuring some physical objects such as amount of flour company produces you can use the same process as in physics.

How do economists see this? Do they see it for example like this: 1.) Firm/Household 2.) Production/Consumption 3.) 10 4.) Apple (or more generally piece

• Firm/Household is not object of measurement that is the level at which you measure something. For example, if you want to measure flour a family owns you can apply your steps 1-4 (or the steps 1, 2 I mentioned earlier) and household is a level/scale at which you are aggregating the ownership of flour.

Ownership of flour could be measured at household, firm, metropolitan, state, country, region etc level. This just defines the level you measure something on. An equivalent of this in physics would be trying to decide whether to measure mass of bricks in kg on a city-level, country level etc. The country, city etc is not measurement object itself it is a level for the measurement object.

• Production/consumption are both composite measurements. For example, consumption would be typically defined as sum of product of price and quantity of consumed products at some point in time at some particular level. So for example, consumption of an individual at time $$t$$ would be given as $$\sum p_{it} q_{it}$$.

So consumption is a composite of a price (which has to be measured separately) and quantity that has to be again measured separately that is summed over all different products that someone consumes. So here you are not talking about single measure to begin with.

how does one define the quantities?

Quantities (in contexts of production/consumption etc) are just counts of objects. If you define your object as a pack of flour then a quantity in economics is just count of the packs of flour however they are defined (e.g. one pack could be defined as some container holding 1kg of flour).

Can one define for example production/consumption as the goods produced by the firm/ consumed by the household?

You can define anything as you want not just in economics but in physics as well. For example, you are not required to follow internationally agreed on definition of metre as a distance light travels in 1/299792458 of a second. You can make up your own metre with different parameters.

This being said production and consumption already have their generally accepted definitions in economics (like metre already has in physics) so if you will define your own measurements in lieu of using already existing and accepted definitions people will get confused.

And if yes, could one say that the value of the quantity refers to the amount of that quantity? E.g. the amount of apples (pieces) produced by the firm/consumed by the household?

Value in economics has double meaning. Typically when economists talk about value of something they do not talk measure of worth. Economists still use value in its mathematical meaning eg "parameter x has value z", but when talking about consumption or production (both composite measures that combine quantity with prices) you would confuse people by using word "value" to mean quantity since typically the word would be used to refer to the worth not quantity in that particular context.

• Thanks for replying! I guess I was confused because in physics (as I learned it), quantity and value are not the same. But as I understand your answer, they are treated the same in economics. To be sure I understood you in the right way: let’s say a consumer consumes 3 units of a good. Then the quantity (of units consumed) is just 3 right? 2 days ago
• @NiklasHein yes
– 1muflon1
2 days ago

The notion of a measurement is a highly contested notion in quantum physics. There is no consensus. What appeared to be a simple notion, appeared in a new guise as a highly complex, discontinuous and non-unitary process.

The notion of measurement in classical physics is much simpler amd is more or less the same notion in classical political economy and is described in the following way:

• quantity and
• units

What has been described, such as:

• quality
• of a certain economic object

Is not usually not seen as part of the measurement. And formally would be pointless as the conservation of energy, for example, requires we add up all the energies no matter what their provenance. Likewise if we are to calculate the GDP, we would add up all the income in a nation, no matter its provenance.

• Can the downvoter please explain what he/she thinks is wrong with my answer? 2 days ago