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ejercicios 4, 5 y 6 resueltos econometría 1, Ejercicios de Econometría

ejercicios resueltos dosier Econometría

Tipo: Ejercicios

2020/2021

Subido el 27/10/2021

ana-garcia-ballester
ana-garcia-ballester 🇪🇸

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EXERCISE 6
A zoologist thinks that there is a linear relationship between the weights and the lengths
of certain mammals. To study this relationship, the following sample of twenty animals
is available:
where WEIGHT is expressed in kilograms and LENGTH in centimetres.
a. Specify a simple linear regression model that relates the weight to the length
of the animals.
𝑊𝐸𝐼𝐺𝐻𝑇!= 𝛽"+𝛽#𝐿𝐸𝑁𝐺𝑇𝐻!+𝑢!
b. Estimate this model with a computer.
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EXERCISE 6

A zoologist thinks that there is a linear relationship between the weights and the lengths of certain mammals. To study this relationship, the following sample of twenty animals is available: where WEIGHT is expressed in kilograms and LENGTH in centimetres. a. Specify a simple linear regression model that relates the weight to the length of the animals. 𝑊𝐸𝐼𝐺𝐻𝑇! = 𝛽" + 𝛽#𝐿𝐸𝑁𝐺𝑇𝐻! + 𝑢! b. Estimate this model with a computer.

Thus, the estimated model will be: 𝑊𝐸𝐼𝐺𝐻𝑇-^! = − 0. 736887 + 0. 0582545 · 𝐿𝐸𝑁𝐺𝑇𝐻! c. Interpret the estimate of the slope. According to my estimated model when LENGHT increases by one centimetre, WEIGHT will increase in 0.0582545 kilograms. That is because 𝛽# = 0. 0582545 (estimate of the slope). d. How much will an animal weigh if it is 45 centimetres long? 𝑊𝐸𝐼𝐺𝐻𝑇-^ = − 0. 736887 + 0. 0582545 · 45 = 1. 8845655 The weight of an animal of a length of 45 centimetres will be 1.8845655 kilograms. e. If an animal is three centimetres longer than other, what difference in weight can be expected? 3 · 𝛽# = 3 · 0. 0582545 = 0. 1747635 If one animal is three centimetres longer than other, the expected difference in weight will be 0. 1747635 kilograms.

𝛽^ :"

𝛽^ :#

EXERCISE 4

Given the following regression models: EXERCISE 5 We start from a model already estimated, that is: 𝑌S^ = 𝛽^ :"^ + 𝛽^ :#^ · 𝑋 We assume that the constant is different from zero (𝑐 ≠ 0 ). 1 st^ step. Multiply the independent variable by the constant. 𝑌S^ = 𝛽^ :"^ +

𝛽^ :#

If X is multiplied by a constant (𝑐 ≠ 0 ), then the slope of the estimated model will be divided by the same constant (𝑐). 2 nd^ step. Multiply the dependent variable by the constant. In a SLRM, if we multiply the dependent variable by a constant, then the estimators will be also multiplied by the same constant.

𝑐 · 𝑌S^ = 𝑐 · 𝛽^ :"^ + 𝑐 ·

𝛽^ :#

Thus, the effect of multiplying both the dependent and the independent variable by the same constant is: 𝑐 · 𝑌S^ = 𝑐 · 𝛽^ :"^ + 𝛽^ :#^ · (𝑐 · 𝑋)