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Regression and Forecasting : Using Data Regression to Predict Sales

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YEAR GNP ln(gnp)
1975 1060 6.966024187
1976 1170 7.064759028
1977 1305 7.17395832
1978 1455 7.28276118
1979 1630 7.396335294
1980 1800 7.495541944
1981 2000 7.60090246
1982 2220 7.705262475
1983 2450 7.803843304
1984 2730 7.912056888

The US BNP during the years 1975-1984 is given in the above table.

a. Plot x = years after 1974 against GNP, and use the plot to describe how to fit a curve that could be used
to predict GNP during future years.

b. When the regression on transformed data is done, we find the B=6.86 and B1=0.105. What is the
prediction for 1985 GNP?

Please see the attached file for the fully formatted problems.

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Solution Summary

Data regression is used to predict sales. The solution is detailed and well presented.

Solution Preview

Please see the attached file.

The regression table can be found on the sheet"regresssion table"

YEAR GNP ln(gnp)
1975 1060 6.966024
1976 1170 7.064759
1977 1305 7.173958
1978 1455 7.282761
1979 1630 7.396335
1980 1800 7.495542
1981 2000 7.600902
1982 2220 7.705262
1983 2450 7.803843
1984 2730 7.912057

The US BNP during the years 1975-1984 is given in the above table.

a. Plot x = years after 1974 against GNP, and use the plot to describe how to fit a curve that could be used
to ...

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  • BSc , Wuhan Univ. China
  • MA, Shandong Univ.
Recent Feedback
  • "Your solution, looks excellent. I recognize things from previous chapters. I have seen the standard deviation formula you used to get 5.154. I do understand the Central Limit Theorem needs the sample size (n) to be greater than 30, we have 100. I do understand the sample mean(s) of the population will follow a normal distribution, and that CLT states the sample mean of population is the population (mean), we have 143.74. But when and WHY do we use the standard deviation formula where you got 5.154. WHEN & Why use standard deviation of the sample mean. I don't understand, why don't we simply use the "100" I understand that standard deviation is the square root of variance. I do understand that the variance is the square of the differences of each sample data value minus the mean. But somehow, why not use 100, why use standard deviation of sample mean? Please help explain."
  • "excellent work"
  • "Thank you so much for all of your help!!! I will be posting another assignment. Please let me know (once posted), if the credits I'm offering is enough or you ! Thanks again!"
  • "Thank you"
  • "Thank you very much for your valuable time and assistance!"
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