John Hicks defined technical change as neutral if it leaves the marginal rate of substitution between capital and labour unchanged for a given capital-labour ratio. This concept is fundamental in growth theory and agricultural productivity analysis to distinguish between factor-augmenting and neutral technological progress.

A declining industry is characterized by a long-term downward trend in demand or profitability. When firms within an industry consistently face negative economic profits, they are incentivized to exit the market. This reduction in the number of active firms leads to a direct decrease in the industry's total aggregate output over time.

The Lorenz curve is a graphical representation of the distribution of income or wealth in a population. It plots the cumulative percentage of total income received against the cumulative percentage of the population, allowing economists to visualize income inequality within a society compared to a line of perfect equality.

Positive economics focuses on objective, empirical analysis of economic phenomena. It seeks to describe 'what is' by using data, statistics, and scientific methods to test hypotheses. By avoiding value judgments and personal opinions, positive economics provides a neutral framework for understanding how economic systems function and predicting the outcomes of various economic policies based on historical evidence.

An industry is defined as a group of firms producing similar goods or services. This classification helps economists and analysts study market competition, supply chains, and the overall economic impact of specific sectors within the broader economy.

Blacker's demographic transition model describes the shift from high birth and death rates to low birth and death rates. The sequence begins with the High Stationary phase (high birth/death rates), moves to the Early Expanding phase (high birth/declining death rates), then to the Low Stationary phase (low birth/death rates), and finally the Declining phase (very low birth/death rates).

Keynesian economics posits that inflation is often driven by an excess of aggregate demand over the economy's productive capacity. This 'demand-pull' inflation occurs when the total demand for goods and services exceeds supply, leading to upward pressure on price levels, a concept central to Keynesian macroeconomic analysis.

While 'underemployment' is a broad category, the specific phenomenon described is more accurately termed 'disguised unemployment' or 'disguised underemployment'. The provided answer 'Underemployment' is a general term, which may lead to confusion regarding the specific nature of the labor inefficiency described.

Theoretical economics is the branch of economics that focuses on developing and testing models and theories to derive fundamental principles. It provides the framework for understanding economic phenomena by abstracting from real-world complexities. While economic analysis involves applying these principles to specific data or events, the actual derivation of the underlying laws and principles is the primary objective of theoretical economics.

Demand-pull inflation occurs when the total demand for goods and services in an economy exceeds the available supply at current prices. This 'too much money chasing too few goods' scenario forces prices upward. It is a common macroeconomic phenomenon during periods of rapid economic growth and high consumer confidence.