Social network analysis is a branch of mathematical social sciences that studies the mathematical properties of social networks, such as the structure, dynamics, and evolution of social networks.

Game theory is a branch of mathematical social sciences that studies the mathematical properties of games, such as the strategies, outcomes, and equilibria of games.

Econometrics is a branch of mathematical social sciences that studies the mathematical properties of economic data, such as the estimation, testing, and forecasting of economic models.

Mathematical psychology is a branch of mathematical social sciences that studies the mathematical properties of human behavior, such as the decision-making, learning, and memory of humans.

Degree is a fundamental concept in social network analysis that measures the number of connections a node has to other nodes in the network.

Nash equilibrium is a fundamental concept in game theory that describes a situation in which no player can improve their outcome by changing their strategy while the other players keep their strategies unchanged.

Regression analysis is a fundamental concept in econometrics that studies the relationship between a dependent variable and one or more independent variables.

Decision theory is a fundamental concept in mathematical psychology that studies the mathematical properties of decision-making, such as the preferences, utilities, and risks of decision-makers.

Social network analysis has a wide range of applications, including identifying influential individuals, detecting communities, analyzing information diffusion, and predicting social behavior.

Game theory has a wide range of applications, including analyzing strategic interactions, designing auctions, developing negotiation strategies, and optimizing resource allocation.

Econometrics has a wide range of applications, including estimating economic models, forecasting economic variables, testing economic hypotheses, and evaluating economic policies.

Mathematical psychology has a wide range of applications, including modeling decision-making, simulating learning processes, developing memory models, and explaining perceptual phenomena.

Social network analysis faces a number of challenges, including collecting reliable data, dealing with large-scale networks, and interpreting complex network structures.

Game theory faces a number of challenges, including modeling complex games, solving games with multiple players, and dealing with incomplete information.

Econometrics faces a number of challenges, including identifying causal relationships, dealing with multicollinearity, and handling heteroskedasticity.

Mathematical psychology faces a number of challenges, including developing realistic models of human behavior, validating models against empirical data, and dealing with individual differences.