Which type of data can be meaningfully added or subtracted, like the cost of university tuition?

The type of data that allows for meaningful addition and subtraction is ratio data. Ratio data has a true zero point, which means that it can provide a full range of meaningful comparisons. In the case of university tuition, when identifying specific amounts, such as $10,000 and $15,000, you can perform arithmetic operations like addition ($10,000 + $5,000 = $15,000) or subtraction ($15,000 - $10,000 = $5,000) to derive significant insights about the costs involved.

Additionally, ratio data maintains the properties of interval data, which include equal intervals between values, but with the added benefit of having a true zero, indicating the absence of the value being measured—like zero dollars in tuition, which has a straightforward interpretation. This feature is particularly important in contexts like finance and economics, where financial statements and budget analysis require precise calculations of costs, revenues, and other monetary values.

While nominal and ordinal data serve different purposes in classification and ranking, respectively, they do not support the arithmetic operations needed for direct comparisons or financial calculations. Ordinal data, even though it can provide an order of values (such as rankings), lacks a consistent scale between values, which makes addition and subtraction invalid