Recent content by 939

  1. 9

    Statistics: given total sum of squares, find R²

    lol yea stupid error, 0.5, sorry :(
  2. 9

    Statistics: given total sum of squares, find R²

    Homework Statement Given: Σ(xi - x̄)² = 500 Σ(yi - ybar)² = 800 (total sum of squares, SST)) Σ(ŷ - ybar)² = 400 (total sum of estimators, SSE) Σ(xi - x̄)²(yi) = 200 Σ(xi - x̄)²(εi) = 0 n = 1000 s² = 4 Find (or explain why you cannot find): β1 β0 variance of β R² Homework Equations [/B]...
  3. 9

    Solve simple regression problem

    Homework Statement Salaries of NBA players related to average points per game: Salary = 1 500 000 + 0.9log(points), n = 150, r^2 = 0.14 1) What is a bad players salary? 2) Interpret the coefficient in front of the aggressor 3) What would be the advantages of running it in log-log form...
  4. 9

    Simple regression: not including the intercept term

    Homework Statement The simple regression model is y = α + βx + u, where u is the error term. If you don't include α, when is β unbiased? Homework Equations y = α + βx + u The Attempt at a Solution Not including α doesn't affect whether β is unbiased because α is a constant.
  5. 9

    Find lagrangian (please check work)

    Sorry. I mean if you were NOT asked to find a maximum or minimum, and were ONLY asked to find the lagrangian and the three partial derivatives - would these two answers be correct regardless of how you solved the constraint function?
  6. 9

    Find lagrangian (please check work)

    The goal was to find an optimal value subject to the constraint... Does it matter then, and how do you know which one to pick? Also, both partial derivatives would be correct, right?
  7. 9

    Find lagrangian (please check work)

    Homework Statement F(x, y) = 96xy - 4x subject to constraint of 11 = x + y Form the lagrangian. Homework Equations F(x, y) = 96xy - 4x subject to constraint of 11 = x + y The Attempt at a Solution My only question is solving 11 = x + y My book says the answer is: L...
  8. 9

    Partial derivative: please check work

    Homework Statement (50 - x - y)(x+y) - x - ((y^2)/2)) simplified: 50X - X^2 - XY - 50Y - XY - Y^2 - X - ((Y^2)/2) Homework Equations 50X - X^2 - XY - 50Y - XY - Y^2 - X - ((Y^2)/2)) The Attempt at a Solution for x: 49 - 2x - 2y for y: 50 - 2x - 3y The book has the same, except -1x and...
  9. 9

    Diagonalize matrix: please check work

    Homework Statement I am pretty sure I went completely wrong but not sure where. Please help! 2 -3 2 -5 Homework Equations 2 -3 2 -5 The Attempt at a Solution (note: I apologize for poor notation) eigenvalues = -4, 1 eigenvectors = (1/√5)(1/2), (1/√10)(3/1) The matrix is not symmetric...
  10. 9

    Eigenvector sign

    Thanks a lot. Just to confirm, the signs in this case do not matter and both answers are correct? I am such a noobie...
  11. 9

    Eigenvector sign

    Homework Statement Find eigenvector for the root -7 of: |2 3| |3 -6| Homework Equations |2 3| |3 -6| The Attempt at a Solution I got 1 -3 But my books says -1 3 I am only wondering if this is possibly the same answer, because when I check my answer by multiplying...
  12. 9

    Total differential, level curve. (please check work)

    Yes, I should've added something about that. Thanks :-).
  13. 9

    Total differential, level curve. (please check work)

    Homework Statement For u(x1, x2) = ax1 + bx2 a) find total differential b) Draw a representative level curve for u = ubar (u with a line over it) c) Find MRS (marginal rate of substitution) Homework Equations u(x1, x2) = ax1 + bx2 The Attempt at a Solution a) fx1 = a fx2...
  14. 9

    Chain rule: y = f(t, t^2, t^3) and y = g(t, h(t), k(t^2))

    Sorry... If it was i.e. y = (x, y), x = (t), y = (t^2) I would get it and there my book says you do the same steps as I listed above. I'm just not sure here... y = f(t, t^2, t^3). Thus, y = dependent. t, t^2, t^3 are independent. Intermediate variables must connect the two... If that is not...
  15. 9

    Partial derivative with chain rule: check work

    Homework Statement If possible, please check my work for any large errors. y = 10kl - √k - √l k = (t/5) + 5 l = 5e^t/10 Evaluate at t = 0 using chain rule. Homework Equations y = 10kl - √k - √l k = (t/5) + 5 l = 5e^t/10 The Attempt at a Solution = ∂y/∂k * dk/dt + ∂y/∂l * dl/dt = (10l -...
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