This is for practice only, NOT TO BE TURNED IN.

From the Econ 100 Lab

The last two rows of machines are newer and run on NT, and the first two rows run on Windows 3.11. Both have the revised ESL running but the access is slightly different.

1. Under NT, from the Desktop, click Start and select Programs, then ESL, and ESLDOS (not the ESLWIN icon).
   Under Windows 3.11, from the Program Manager, click the ESL group and then ESLDOS (not ESLWIN).
2. When the default options for ESL comes, type the number zero and <enter>.
3. Next type data4-1. ESL will load the data set and ask for the name of the input command file. Choose the name as ps1inp (which stands for Practice Session 1 input file). All the commands you type from now on will be saved under the name ps1inp.txt, which is an ASCII text file.
4. Next you will be asked for the name of the output file. Choose the name ps1out. The results of your analyses that appear on screen will be stored under the name ps1out.txt.
5. When you see the ESL prompt ?, type each of the following lines and press <enter>.

The specified semicolon is important.
logs 2 3 4 ; (this will create logarithms of the variables listed)
ols 1 0 2 3 4 5 6 7 ; (this estimates a "kitchen sink" model by OLS)
You will get the message that there is exact multicollinearity. To identify the culprit,
type:
corr 2 3 4 5 6 7 ;
to get the correlation matrix of the right-hand side variables. Note that variables 3
(bedrooms) and 6 (log of bedrooms) are perfectly correlated. This means that you
should use only one of them in the model. Next type:
ols 1 0 2 4 5 6 7 ;

At any time in the following session if you want to scroll back to view previous
results, simple type: scroll (without the semicolon).

6. Identify the regression coefficient that is least significant and omit the corresponding variable using the omit command. For example, omit 2 ;
   In the last column of the output, one asterisk means that the coefficient is significant
   at levels between 5 and 10, two asterisks mean that the coefficient is significant at
   levels between 1 and 5, and three asterisks mean that coefficient is significant at
   levels below 1 percent (explain whether more/less asterisks are preferable and why).

   Repeat the above step and omit variables one at a time until all the remaining
   regression coefficients are significant at the 10 percent level (ignore the constant term
   in all this and never omit it).
   If you want to learn about other ESL commands, type:help ; .
   When you are finished, type quit to exit ESL. You will be informed of the exact path names for your input commands and output results. Notepad (Edit in the Windows 3.11 machines) will then be invoked to view the results. If you want to "maximize" the page, click the middle button on the top right-hand corner.
   To print the results, click File in the top left-hand corner and select Print. When done, click the x on the top right-hand corner to exit ESL and return to the desktop.

   If you want to see how ESLWIN works, then carry out the following steps:
   Under NT: From the Desktop, click Start and select Programs, then ESL, and ESLWIN.
   Under Windows 3.11: From the Program Manager, click the ESL group, and ESLWIN. Then choose Estimate, Interactive, and textbook data set data4-1. The remaining steps are identical to the above.
   
   Using the model selection criteria discussed in Section 4.3, the significance of the
   regression coefficients, and the omitted variable bias studied in Section 4.5, choose the "best" model. How does your model compare with the linear models in Table 4.3 and the model presented in Example 6.1?
   
   
   From your personal computer at home
   
   First of all, install ESL and ESLWIN using the directions given at the top of Page C-2. If you don't have a copy of the disk, you can get a copy from me (I have only a few copies left). Next, use the ESL update link in the class Web page at http://weber.ucsd.edu/~rramanat/ec120c/fall98
   and download the files esl.exe, esl.cfg, and esl.hlp. Copy esl.cfg to the root directory in C: and the other two files over the old files in the directory C:\ESL.
   
   If an ESLWIN icon has already been created in your Desktop, then double click that, and select Start, Programs, ESL, and then ESLWIN. Then choose Estimate, Interactive, and textbook data set data4-1. The remaining steps are identical to the above. ESLWIN is a useful way to reproduce all the Practice Computer Sessions in the book.
   
   You can also run ESL from MSDOS. To do that, first use the Desktop Explorer (NOT the Internet Explorer) to go to the directory C:\ESL, and click esl.exe. Then hold left mouse button down and drag the mouse to a place outside the Explorer window to Desktop. Windows/NT will create the short cut to ESL through MSDOS. Thereafter, you can click this icon from the Desktop to run ESL.