Let "fit" summarize how far the in-sample observations are from
the fitted model; e.g., fit=100 indicates worse fit than fit=50.
Let "penalty" be increasing in the size of a model, specifically
the number of parameters in the model, given the same sample size;
e.g., given sample size 80, penalty is larger for a model with 10
parameters than for a model with 5 parameters. To prevent
overfitting when choosing a forecasting model, you could
maximize (fit + penalty)
minimize (fit...
(a) Explain how you determine to fit either multiplicative or
additive
decomposition model to a time series data.
(b) The following table gives quarterly sales figures of a
well-known brand of
designer bag in a shop in City center in the last two years.
Year 201
7
201
8
201
9
Quarte
r
1 2 3 4 1 2 3 4 1 2 3 4
Sales 10 15 25 34 18 19 33 38 14 27 29 46
You have...
When fitting a multiple regression model, you should check for
independence of observations and the absence of multicollinearity.
Discuss how you would check appropriate statistics and/or
plots.
(a) When we run a multiple regression, we hope to be able to
generalize the sample model to the entire population. To do this,
several assumptions must be met including: No Multicollinearity
Homoscedasticity Independent Errors Normally-distributed
Errors
Explain what is meant by each of these assumptions and describe the...
Exercise 5.4
Refer back to exercise 2.2. Suppose that you fit the model to 20
data points and found that your F – value for testing the model is
useful is 49.75.
Exercise 2.2
A hotel manager is concerned about hotel room rates for a large
chain of hotels. The variables to be used in this research is
defined as follows:
Y = the daily rate of a room
X1 = the population of the city
X2 = the rating...
From a spending model perspective, explain the causes of a
recession.
To get you started, consider that our recent recession seems
to demonstrate that expenditures and incomes depend on each
other.
If markets do not self-adjust, how can a decline in spending
lead to a negative process that ruins an economy? (Consider
implications of gaps in the "Keynesian Cross" and/or the "Aggregate
Demand/Aggregate Supply Diagram" to illustrate your points.)
Hints -- Within your answers, consider the following:
--Identify and summarize...
What might a better model to predict fertility look
like, if you could get data on any additional variables at the
country level? Be sure to explain the THEORY behind including these
new variables in your analysis.
Subject Econometrics
Consider a regression model
Yi=β0+β1Xi+ui
and suppose from a sample of 10 observations you are provided the
following information:
∑10i=1Yi=71; ∑10i=1Xi=42; ∑10i=1XiYi=308;
∑10i=1X2i=196
Given this information, what is the predicted value of
Y, i.e.,Yˆ for x = 12?
1. 14
2. 11
3. 13
4. 12
5. 15
Consider the model Ci= β0+β1 Yi+ ui. Suppose you run this
regression using OLS and get the following results: b0=-3.13437;
SE(b0)=0.959254; b1=1.46693; SE(b1)=0.0697828; R-squared=0.130357;
and SER=8.769363. Note that b0 and b1 the OLS estimate of b0 and
b1, respectively. The total number of observations is 2950. The
following values are relevant for assessing goodness of fit of the
estimated model with the exception of
A. 0.130357
B. 8.769363
C. 1.46693
D. none of these
Assume that the population distribution of BMI among adults over 18 is Normal with mean μ = 38 and standard deviation σ = 12 and suppose the you have an SRS of 4 adults. What is the probability that your sample will have a mean BMI of 53 or greater? Use Table A: Standard Normal Table and round your answer to 4 decimal places.