Mean square error (MSE) = 1/nσ (xi-μ) 2
Standard deviation (σ) = sqrt (1/nσ (xi-μ) 2)
Where xi represents sample data, μ represents sample mean, and n represents sample number.
Knowledge expansion
"Formula" refers to the formula used to express the quantitative relationship in mathematics, physics, chemistry and other disciplines. It consists of symbols, numbers, letters and other elements as well as operational symbols (addition, subtraction, multiplication, division, etc.). ), you can express a rule or calculation method concisely and clearly.
In mathematics, formula is an important tool, which can help us solve various problems. For example, you can use the square difference formula (A+B) (A-B) = A 2-B 2 to calculate the square difference of two numbers; Pythagorean theorem formula (A, B and C are three sides of a right triangle, while ∠C is a right angle) can be used to prove a right triangle.
Besides mathematics, formulas also play an important role in physics, chemistry and other disciplines. For example, Newton's second law formula F=ma (where f stands for force, m stands for mass and a stands for acceleration) can be used to calculate the acceleration of an object; Chemical equations can be used to express the reaction relationship and reaction conditions between substances in chemical reactions.
In a word, the formula is a simple tool to express the quantitative relationship, which can help us solve various problems and improve work efficiency. Formulas play an important role in mathematics, physics, chemistry and other disciplines, and are also one of the foundations for us to learn these disciplines.
Formulas are widely used not only in mathematics, physics and chemistry, but also in daily life and work.
In daily life and work, formulas can be used to solve various practical problems. For example, in investment and financial management, you can use formulas to calculate the return on investment and the proportion of asset allocation. In engineering calculation, this formula can be used to calculate the strength and stress distribution of materials. In statistical analysis, formulas can be used to calculate mean and standard deviation.
In addition, the formula can also be used to simplify the calculation process and remember complex relationships. For example, using formulas, we can simplify multiple complicated calculation steps into a simple formula, thus improving the calculation efficiency. At the same time, some complex relationships can be expressed concisely through formulas, so as to better understand and remember these relationships.
In a word, formulas are widely used tools in mathematics, physics, chemistry and other disciplines as well as in daily life and work. It can help us solve various problems and improve work efficiency, and it is also one of the foundations for us to learn these subjects. Therefore, it is very important for students and workers to master the meaning and application of the formula.