The measurement of economic worth over time is the problem of relating past prices, costs, values and proportions of social production to current ones.
Finally, concepts such as cash money economies may not exist in past periods, nor ideas like wage labour or capital investment.
Marxist and political economic value, neoclassical marginalist, and other ideas regarding proportion of social product not measured in money terms have arisen.
Historical series computed from statistical data sets, or estimated from archival records have a number of other problems, including changing consumption bundles, consumption bundles not representing standard measures, and changes to the structure of social worth itself such as the move to wage labour and market economies.
Contemporary wage price series are the result of the normal operation of government economic statistics units, and are often produced as part of the National income accounts.