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The answer to the 100 questions of disjunctive calculation is needed now Please list them one by one, for example, 2 + 90 * 20 = 2 + 1800 = 1802
Seek 20 4 grade volume 1 off type calculation questions
Please
Sign of correlation coefficient and regression coefficient
Correlation coefficient and regression coefficient
Do the binary regression equation y = a + b1x1 + b2x2, get B2 is negative, that is, y and X2 are inversely proportional, find y and X2 two groups of data correlation coefficient is positive, that is, y and X2 are proportional, ask in the end y and X2 are proportional or inversely proportional, why
First of all, we need to understand two concepts: direct ratio and positive correlation. Positive correlation: the independent variable increases, and the dependent variable also increases. Direct ratio: the independent variable increases by K times, and the dependent variable also increases by K times. Inverse ratio: the independent variable increases by K times, and the dependent variable also increases by 1 / K times
Regression coefficient and correlation coefficient have the same sign. Why?
Suppose that the regression equation is b0x + A and B is the regression coefficient. Then B0 must be the value of B which makes E [y-bx-a] ^ 2 obtain the minimum value
Then we can get the minimum E [y-bx-a] ^ 2 when B = cov (x, y) / D (x)
Therefore, B0 = cov (x, y) / D (x) has the same sign as cov (x, y), that is, it has the same sign as the correlation coefficient
(2009 · Wuhan simulation) consists of a set of sample data (x1, Y1), (X2, Y2), (X3, Y3) The linear regression equation ̂ y = BX + a obtained by (xn, yn) is ()
A. The straight line ̂ y = BX + a must pass through the point (. X,. Y); B. the straight line ̂ y = BX + a must pass through at least (x1, Y1), (X2, Y2), (X3, Y3) The slope of the line ̂ y = BX + A is b = Ni = 1xiyi − n.X ·. YNi = 1x2i − n.x2; D. the line ̂ y = BX + A and the points (x1, Y1), (X2, Y2), (X3, Y3) The deviation of (xn, yn) q = Ni = 1 [Yi − (bxi + a)] 2 is the smallest of the deviations of all lines on the coordinate plane from these points
The linear regression line must pass through the center point of the sample, so a is correct. The linear regression line does not necessarily pass through a point in the sample data. This is the line that can best reflect the change trend of this group of data, but it is not necessarily on the line, so B is incorrect. According to the least square method, C is correct, and according to the meaning of the linear regression line, D is correct, so B is selected
What is the practical significance of studying simple linear regression equation?
① From a group of data, we can determine the quantitative relationship between some variables, that is, to establish a mathematical model and estimate the unknown parameters. The commonly used method to estimate the parameters is the least square method
There are the following corresponding data between the advertising expenses X and the sales amount y of a certain product: X 24568 y 30 40 60 50 70 (1) draw the scatter diagram; (2) find the linear regression equation; (3) predict the sales amount when the advertising expenses are 7 (million yuan)
(1) (2). X = 5,. Y = 50.5i = 1x2i = 145, 5I = 1xiyi = 1380 let the regression equation be y = BX + A, then B = 5I = 1xiyi-5. X.y / 5I = 1x2i-5. X2 = 1380-5 × 5 × 50 / 145-5 × 52 = 6.5A =. Y − b.x = 50 − 6.5 × 5 = 17.5, so the regression equation is y = 6.5x + 17.5 (3) when x = 7, y = 6.5 × 7 + 17.5 = 63, so when the advertising expense is 7 (million yuan), the sales is about 63 (million yuan)
How to use Excel to solve binary linear regression equation? Specific point
Linest function specific how to operate, why I can only do one variable
Linest function all show all hide this paper introduces the Microsoft Office Excel Linest function (function: function is a formula written in advance, can perform operations on one or more values, and return one or more values. Function can simplify and shorten the formula in the worksheet, especially in the formula execution is very difficult
Which excel function can be used to find the coefficients a and B of linear regression equation
The Linest function returns an array with various parameters
For slope and intercept, there are also special functions slope and intercept
The steps of solving linear regression equation with calculator
There is no understand, we high school, with the pen trouble
Here are the steps to use the "Shennan wild goose" brand computer. If there is a manual, you can see that there are two variables X and Y in the linear regression. To input, first press mode 3, then press x1, Y1, and then press
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