Added several new data sets and several new end of chapter exercises. Converted ASCII data sets to EXCEL and EVIEWS formats. In computer outputs presented in the book, all references to commands have been deleted and only essential parts that are basically independent of the software that readers use have been kept, so that the comments in these outputs will be beneficial to all.

**Chapter 1**

Includes a discussion of different types of data: experimental,
observational, and sample survey.

**Chapter 2**

Example 2.9 is new. Rest are moved up by one. The section on joint
probabilities has an extensive discussion of conditional probability,
conditional expectation, and conditional variance. Properties
involving multivariate distributions have been moved from the appendix
to the chapter. The reference section has been expanded.

**Chapter 3**

All the assumptions on the error terms have been stated as conditional
on given X. Proofs of unbiasedness and the Gauss-Markov Theorem are
initially done with X given and then extended to the case where it is a
random variable.

**Chapter 4**

Example 4.2 is new. Rest are moved up by one.
Added DATA4-16 and DATA4-17.

Added a section on generating the forecast and confidence interval for
the dependent variable in a multiple regression model.

Added a section on important comments about interpreting regression
coefficients, especially those for variables measured as percentages or
proportions.

**Chapter 6**

Added a discussion and a table summarizing the interpretation of
regression coefficients in models involving logarithms of variables.

**Chapter 7**

Added DATA7-24, DATA7-25, and DATA7-26.

Added a section on the modified interpretation of dummy
coefficients in the case of log-linear models.

**Chapter 9**

Added DATA9-13.

**Chapter 10**

Replaced Example 10.5 by a new one and added Example 10.6. Remaining
examples have been renumbered. Added a section on VAR models and
another on panel data. Example 10.9 is new.

**Chapter 11**

Extends the forecast combination section to include serial correlation,
ARCH effects, and time-varying weights.

**Chapter 14**

Added a section on index numbers. Added section on Econ Lit software.

**Appendix C**

Data sets are now available in a variety of formats; ASCII (that is,
text), B34S, EVIEWS, EXCEL, GRETL, PcGive, and SHAZAM. The appendix
also describes where these data sets are available and provides a brief
introduction to the econometrics software packages B34S, EVIEWS, GRETL,
PcGive, and SHAZAM, with a link to other software packages.

**Appendix D**

Added descriptions of new data sets.