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ECONOMICS AND ELECTING THE PRESIDENT

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Page 1: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

ECONOMICS AND ELECTING THE PRESIDENT

Page 3: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Presidential Election Links 

http://fairmodel.econ.yale.edu/ http://www.apsanet.org/content_58382.cfm http://www.douglas-hibbs.com/Election2012/2012Election-MainPage.htm

Page 4: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Economic Growth and the United States Presidency:Can You Evaluate the Players Without a Scorecard?

David J. BerriDepartment of Applied Economics

California State University – BakersfieldBakersfield, California 93311

[email protected]

James PeachP. O. Box 30001/ MSC 3CQDepartment of Economics

New Mexico State UniversityLas Cruces, NM 88003

[email protected]

Page 5: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

ABSTRACT

In several academic papers and a book, Ray Fair (1978, 1996, 2002) has demonstrated a link between the state of the macroeconomy and the outcome of the Presidential Election in the United States. Beginning with the 1916 election, Fair’s model, based on such factors as economic growth, inflation, and incumbency, was able to accurately predict the winner in virtually every election. The purpose of this research is to take the Fair model back to the 19th century. The question we address is as follows: Can a version of Fair’s model accurately predict in an environment where economic data was not made available to the voter?

Page 6: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

LOUIS BEAN (1948) HOW TO PREDICT ELECTIONS

“Business depressions played a powerful role in throwing the Republicans out of office in 1874, after 1908, and in 1932, and they had exactly the same influence in ousting Democrats after the panic of 1858 and during the economic setbacks of 1894 and 1920.”

“Harding in 1920, McKinley in 1896, and Cleveland in 1884 were also depression-made presidents. Had the deciding electoral vote been cast for the candidate who had the majority of the popular vote in 1876, Tilden too, would have been a depression-made President.”

Page 7: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

THE WORK OF RAY FAIR

Fair, Ray C. 1978. “The Effect of Economic Events on Votes for President.” The Review of Economics and Statistics (Vol. LX, No. 2):159-173 May 1978.

Fair, Ray C. 1978. “The Effect of Economic Events on Votes for President: 1980 Results.” The Review of Economics and Statistics (Vol. 64, No. 2):322-25 May 1978.

Fair, Ray. C. 1996. “Econometrics and Presidential Elections.” Journal of Economic Perspectives (Vol. 10, No 3):89-102 (Summer 1996).

Fair, Ray C. 2002. “The Effect of Economic Events on Votes for President: 2000 Update.” http://fairmodel.econ.yale.edu/RAYFAIR/PDF/2002DHTM Downloaded Feb 2, 2006.

Fair, Ray C. 2002. Predicting Presidential Elections and other things. Stanford: Stanford Business Books.

Page 8: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

A FAIR MODEL

VOTE= a1 + a2GROWTH+ a3INFLATION +

a4PARTY + a5PERSON + a6DURATION + a7GOODNEWS + ε

Page 9: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

DEFINING THE VARIABLES EMPLOYEDHTTP://FAIRMODEL.ECON.YALE.EDU/RAYFAIR/PDF/2002DHTM.HTM

VOTE = Incumbent share of the two-party presidential vote.

GROWTH = annual growth rate of real per capita GDP in the first three quarters of the election year.

INFLATION = absolute value of the growth rate of the GDP deflator in the first 15 quarters of the administration (annual rate) except for 1920, 1944, and 1948, where the values are zero.

Page 10: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

DEFINING THE VARIABLES EMPLOYEDHTTP://FAIRMODEL.ECON.YALE.EDU/RAYFAIR/PDF/2002DHTM.HTM

PARTY = 1 if Democrats are in power, = -1 if Republicans are in power

PERSON = 1 if the president is running, = 0 otherwise

DURATION = 0 if the incumbent party has been in power for one term, 1 if the incumbent party has been in power for two consecutive terms, 1.25 if the incumbent party has been in power for three consecutive terms, 1.50 for four consecutive terms, and so on.

WAR = 1 for the elections of 1920, 1944, and 1948 and 0 otherwise

GOODNEWS = number of quarters in the first 15 quarters of the administration in which the growth rate of real per capita GDP is greater than 3.2 percent at an annual rate except for 1920, 1944, and 1948, where the values are zero.

Page 11: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Table One The Accuracy of the Fair Model

1916-2000

Year Incumbent Party

Candidate Challenger

Actual VOTE received by incumbent

Predicted VOTE received by incumbent Error

Actual Winner

Predicted Winner

1916 Wilson Hughes 51.7 50.9 -0.8 Wilson Wilson 1920 Cox Harding 36.1 39.2 3.1 Harding Harding 1924 Coolidge Davis 58.2 57.3 -1.0 Coolidge Coolidge 1928 Hoover Smith 58.8 57.6 -1.2 Hoover Hoover 1932 Hoover Roosevelt 40.8 38.8 -2.1 Roosevelt Roosevelt 1936 Roosevelt Landon 62.5 63.8 1.4 Roosevelt Roosevelt 1940 Roosevelt Willkie 55.0 55.7 0.7 Roosevelt Roosevelt 1944 Roosevelt Dewey 53.8 52.5 -1.2 Roosevelt Roosevelt 1948 Truman Dewey 52.4 50.5 -1.8 Truman Truman 1952 Stevenson Eisenhower 44.6 44.4 -0.2 Eisenhower Eisenhower 1956 Eisenhower Stevenson 57.8 57.3 -0.5 Eisenhower Eisenhower 1960 Nixon Kennedy 49.9 51.6 1.7 Kennedy Nixon 1964 L. Johnson Goldwater 61.3 61.1 -0.3 L. Johnson L. Johnson 1968 Humphrey Nixon 49.6 50.2 0.6 Nixon Humphrey 1972 Nixon McGovern 61.8 59.4 -2.4 Nixon Nixon 1976 Ford Carter 48.9 48.9 0.0 Carter Carter 1980 Carter Reagan 44.7 45.7 1.0 Reagan Reagan 1984 Reagan Mondale 59.2 62.0 2.9 Reagan Reagan 1988 G. Bush Dukakis 53.9 51.3 -2.6 G. Bush G. Bush 1992 G. Bush Clinton 46.5 51.7 5.1 Clinton G. Bush 1996 Clinton Dole 54.7 53.7 -1.0 Clinton Clinton 2000 Gore G.W. Bush 50.3 48.9 -1.3 G.W. Bush G.W. Bush

Source: http://fairmodel.econ.yale.edu/RAYFAIR/PDF/2002DHTM.HTM

Page 12: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

SUMMARIZING FAIR: 1916-2000 Only incorrect in three elections: 1960, 1964, 1992.

Average absolute error: 1.5

Results are driven by economic variables with no consideration of a candidate’s appearance, debating talents, advertisements, or general campaign skills.

Page 13: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

TAKING FAIR BACK TO 1824 New measures of growth and inflation are needed.

Louis Johnston and Samuel H. Williamson, "The Annual Real and Nominal GDP for the United States, 1789 - Present." Economic History Services, April 2002, URL : http://www.eh.net/hmit/gdp/

This data has been updated. Updated data did not change our general findings.

Page 14: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

THE MODELS TO BE ESTIMATED

Model 1 Original Fair Model (1916-2000)

Model 2

Fair Model with new measures of GROWTH and INFLATION

(1916-2000)

Model 3

Fair Model with new measures of GROWTH and INFLATION,

no GOODNEWS (1916-2000)

Model 4

Fair Model with new measures of GROWTH and INFLATION,

no GOODNEWS (1916-2004)

Model 5

Fair Model with new measures of GROWTH and INFLATION,

no GOODNEWS (1824-1912)

Model 6

Fair Model with new measures of GROWTH and INFLATION,

no GOODNEWS (1824-2004)

Page 15: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Table Three Various Estimates of Fair’s Model

Dependent Variable is VOTE White Heteroskedasticity-Consistent Standard Errors & Covariance

Model 1 Model 2 Model 3 Model 4 Model 5 Model 6

Sample: 1916-2000 1916-2000 1916-2000 1916-2004 1824-1912 1824-2004

GROWTH 0.691* 0.457* 0.409** 0.413** -0.135 0.342

(6.169) (3.526) (2.569) (2.649) (-0.560) (1.577)

INFLATION -0.775* -0.808* -0.988* -0.943* 0.438 -0.191

(3.915) (4.132) (5.405) (5.051) (0.511) (0.731)

PARTY -2.713* -2.054** -1.644*** -1.252 0.647 -0.594

(5.434) (2.644) (1.946) (1.363) (0.344) (0.580)

PERSON 3.251*** 2.145 1.701 1.578 -0.372 1.705

(1.837) (1.007) (0.698) (0.663) (0.083) (0.625)

DURATION -3.628** -4.238** -5.216** -4.519*** 1.414 -0.448

(2.517) (2.410) (2.315) (1.968) (0.611) (0.208)

WAR 3.855 5.268 2.905 2.262 -1.881 -0.835

(1.213) (1.369) (1.102) (0.832) (0.102) (0.214)

GOODNEWS 0.837** 0.539

(2.932) (1.238)

INTERCEPT 49.607* 52.871* 57.769* 56.892 48.458 50.889

(19.550) (15.512) (18.169) (17.736) (10.618) (15.184)

R-Square 0.923 0.845 0.828 0.769 0.093 0.116

Adjusted R-Square 0.885 0.767 0.759 0.683 -0.248 -0.020 F-Statistic 24.000* 10.888* 12.015* 8.883* 0.272 0.850 Observation 22 22 22 23 23 46

t-statistics in parenthesis below each coefficient. * - Significant at the 1% level ** - Significant at the 5% level *** - Significant at the 10% level

Page 16: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Table Four The Accuracy of the Fair Model

1824-1912 Forecast Based on Model 3

Year Incumbent Party

Candidate Challenger

Actual VOTE received by incumbent

Predicted VOTE received by incumbent Error

Actual Winner

Predicted Winner

1824 Jackson J.Q. Adams 57.2 39.8 17.4 J.Q. Adams* J.Q. Adams 1828 J.Q. Adams Jackson 43.8 56.9 13.1 Jackson J.Q. Adams 1832 Jackson Clay 59.2 58.0 1.2 Jackson Jackson 1836 Van Buren W. Harrison 58.1 43.7 14.4 Van Buren W. Harrison 1840 Van Buren W. Harrison 47.0 51.4 4.4 W. Harrison Van Buren 1844 Clay Polk 49.3 58.6 9.4 Polk Clay 1848 Cass Taylor 47.3 53.5 6.2 Taylor Cass 1852 Scott Pierce 46.3 62.0 15.7 Pierce Scott 1856 Buchanan Fremont 57.8 55.2 2.6 Buchanan Buchanan 1860 Breckinridge Lincoln 31.2 56.4 25.2 Lincoln Breckinridge 1864 Lincoln McClellan 55.0 42.9 12.1 Lincoln McClellan 1868 Grant Seymour 52.7 48.5 4.2 Grant Seymour 1872 Grant Greeley 55.9 55.9 0.0 Grant Grant 1876 Hayes Tilden 48.5 50.3 1.8 Hayes* Hayes 1880 Garfield Hancock 50.0 50.0 0.2 Garfield Hancock 1884 Blaine Cleveland 49.9 45.1 4.8 Cleveland Cleveland 1888 Cleveland B. Harrison 50.4 59.1 8.7 B.Harrison* Cleveland 1892 B. Harrison Cleveland 48.3 61.2 13.0 Cleveland B. Harrison 1896 Bryan McKinley 47.8 53.7 5.9 McKinley Bryan 1900 McKinley Bryan 53.2 59.5 6.3 McKinley McKinley 1904 T. Roosevelt Parker 60.0 49.9 10.1 T. Roosevelt Parker 1908 Taft Bryan 54.5 46.8 7.6 Taft Bryan 1912 Taft/Roosevelt Wilson 54.7 50.6 4.1 Wilson* Taft-Roosevelt

* - did not win popular vote

Page 17: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

WHY DOES THE FAIR MODEL FAIR POORLY BEFORE 1916?

Economic data did not exist.

U.S. economy not integrated.

Federal government was not held responsible for the macroeconomy.

Non-economic issues were more important in the 19th century.

Page 18: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Econometrics and Presidential Elections

Larry M. Bartels

Page 19: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

OVERVIEW OF THE FAIR MODEL One of the most interesting aspects of Fair's essay is

the unusually frank and detailed description it provides of the enormous amount of exploratory research underlying published analyses of aggregate election outcomes. What is the relevant sample period? Which economic variables matter? Measured over what time span? What does one do with third party votes, war years, or an unelected incumbent? In fewer than a dozen pages, Fair raises and resolves many such questions, as any data analyst must. In the process, he makes clear how much of what Leamer (1978) has referred to as “specification uncertainty” plagues this (or any other) statistical analysis of presidential election outcomes.

Page 20: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

CHOOSING A MODEL ….(Fair’s) choice of model specification seems to have been guided by goodness-of-fit considerations rather than by a priori political or economic considerations. His data set begins in 1916 because “some experimentation . . . using observations prior to 1916" produced results that “were not as good.” Gerald Ford is sometimes counted as an incumbent and sometimes not, depending upon which treatment “improves the fit of the equation.” Revised economic data produced significant changes in several key coefficients, prompting renewed searching “to see which set of economic variables led to the best fit,” and so on.

Page 21: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

WHAT HAVE WE LEARNED? What most electoral scholars really care about is what the

relationship between economic conditions and election outcomes tells us about voting behavior and democratic accountability.

On that score, what have we learned, and what have we yet to learn?

The clearest and most significant implication of aggregate election analyses is that objective economic conditions -- not clever television ads, debate performances, or the other ephemera of day-to-day campaigning -- are the single most important influence upon an incumbent president's prospects for reelection.

Despite a good deal of uncertainty regarding the exact form of the relationship, the relevant time horizon, and the relative importance of specific economic indicators, there can be no doubt that presidential elections are, in significant part, referenda on the state of the economy.

Page 22: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

WHY DOES THE ECONOMY MATTER? Do economic conditions matter because people vote

their own pocketbooks, or because they respond to changes in the whole nation's economic condition?

The work of Markus (1988) and others has demonstrated that personal and national economic fortunes are both important. However, this demonstration does almost nothing to resolve the related question of whether voters' underlying motivations are selfish or altruistic. (Selfish voters could rationally base forecasts of their own future incomes on recent changes in the national economy, while altruistic voters could rationally base expectations regarding their fellow citizens' future economic fortunes on their own recent economic experience.)

Page 23: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

MORE ON “WHY”… Can voters untangle the complex contributions of the president and other actors to the making of government policy? Can they untangle the even more complex contributions of government policy, exogenous economic forces, and dumb luck to observed levels of economic growth, wage changes, unemployment, or inflation?

Alesina, Londregan, and Rosenthal (1993) attempted to distinguish between “rational” and “naive” economic voting by estimating separate electoral effects for economic “shocks” and economic growth that was “predictable” on the basis of previous growth, partisan effects, and military mobilization. They found no significant difference between these potentially distinct effects, a result they interpreted (1993, 23) as “consistent with the hypothesis of naive retrospective voting.”

Page 24: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

AND MORE ON “WHY”… …we know remarkably little about why voters reward the incumbent president for prosperity or punish him for economic distress.

Do they have any rational basis for supposing that economic conditions in the election year are indicative of future conditions if the incumbent is reelected? (As far as I know, nobody has demonstrated such a connection.)

Do they know or care what, if anything, the out party would do differently? Or, as Ferejohn (1986) and others would have it, are they simply holding up their end of a simple-minded implicit contract intended to extract whatever effort a self-interested incumbent may be able to exert on their behalf -- the only sort of accountability feasible in a situation marked by massive uncertainty and asymmetric information?

Page 25: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

MY OWN THOUGHTS…

Three voters in the election… Republicans (vote Republican) Democrates (vote Democrat) Independents

The only free agents are independents. These are voters who care so little, they don’t join a party. And these are the voters that matter.

Why the economy? It is the one issue that matters to the independent.

Page 26: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

POLITICS AND FOOTBALL…Some football coaches believe the run sets up the pass. Others think the pass sets up the run. Fans, though, don’t care. You win, you keep your job. You lose, you lose your job.

Applied to politics… some people believe in smaller government and low taxes. Others believe in more government to solve problems.

Independents, though, don’t care. The economy does well, you keep your job. If not, your fired. What the politician believes is simply not relevant.

Page 27: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Writing an academic paper

1. Introduction (tell cute story)2. Literature Review3. Describe Data4. Create model:

1. Identify dependent variable2. Identify independent variables3. State hypothesis4. Estimate model

Page 28: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

DATA SUMMARY AND DESCRIPTION

Population Parameters – Summary and descriptive measures for the population.

Sample Statistics – Summary and descriptive measures for a sample.

NOTE: We rarely have data for the population. Hence we need to be able to draw inferences from a sample.

Page 29: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

MEASURES OF CENTRAL TENDENCY

Mean – The average Issue: You must note the distribution of

the sample. If it is unbalanced the mean may be misleading.

Median – “Middle” observation

Page 30: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

SYMMETRICAL VS. SKEWNESS

Symmetrical – A balanced distribution. Median = Mean

Skewness – A lack of balance. Skewed to the left: Median > Mean

Skewed to the right: Median < Mean

If skewness is observed one may wish to examine a sub-sample of the data.

Page 31: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

MEASURES OF DISPERSION

Range – Difference between the largest and smallest sample observations. Only considers the extremes of the sample

Solution: Inter-quartile or percentile range

Variance and Standard Deviation Sample Variance – Average squared deviation

from the sample mean.

Sample Standard Deviation – Squared root of the sample variance.

Page 32: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

COEFFICIENT OF VARIATION

Coefficient of variation – Standard deviation divided by the mean.

A measure that does not rely on the size of the observations or the unit of measurement.

This is used to compare relative dispersion across a variety of data.

Page 33: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Hypothesis Testing Hypothesis Testing – Statistical experiment

used to measure the reasonableness of a given theory or premise NOTE: WE DO NOT “PROVE” A THEORY

Type I Error – Incorrect rejection of a ‘true’ hypothesis.

Type II Error – Failure to reject a ‘false’ hypothesis.

Page 34: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Regression AnalysisDefinitions

Regression analysis – statistical method for describing the relationship between a dependent variable Y and independent variable(s) X.

Deterministic Relation = An identity A relationship that is known with certainty.

Statistical Relation – An inexact relation

Page 35: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Regression AnalysisTypes of Data Time series – A daily, weekly, monthly, or annual

sequence of data. i.e. GDP data for the United States from 1950 to 2012

Cross-section – Data from a common point in time. i.e. GDP data for OECD nations in 1986.

Panel data – Data that combines both cross-section and time-series data. i.e. GDP data for OECD nations from 1960 to 2012.

Page 36: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Steps in Regression Analysis1. Specify the dependent and independent

variable(s) to be analyzed

2. Obtain reliable data.

3. Estimate the model.

4. Interpret the regression results.

Page 37: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Specifying the Regression AnalysisThe choice of independent variables

Univariate analysis = Simple regression model - A regression model with only one independent variable. Issue: Cannot impose ceteris paribus

Multivariate analysis = Multiple regression model - A regression model with multiple independent variables.

Page 38: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Univariate Analysis

Y = a + bX Where Y = The Dependent Variable, or

what you are trying to explain (or predict).

X = The Independent Variable, or what you believe explains Y.

a = the y-intercept or constant term.

b = the slope or coefficient

Page 39: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

The Least Squares Model Ordinary Least Squares: a statistical

method that chooses the regression line by minimizing the squared distance between the data points and the regression line.

Why not sum the errors? Generally equals zero.

Why not take the absolute value of the errors? We wish to emphasize large errors.

Page 40: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

The slope coefficient How do we interpret the slope coefficient? Example: Winning percentage = -0.830 +

0.014*(Points per game) Each additional one point per game

results in a 0.014 increase in winning percentage.

How many wins is this? 1.1 over an 82 game season.

Is this the ‘truth’? We never know the truth, we are simply attempting to derive estimates.

Is this a ‘good’ estimate? Clearly points alone do not explain wins.

Page 41: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

The constant term

How do we interpret the constant term? The constant term must be included in the regression, or else we

are forcing the regression line through zero. The constant term is used to impose a zero mean for the error

term, hence it acts as a garbage collector. In other words, it captures all the factors not explicitly utilized in the equation.

The constant term is theoretically the value of Y when X is zero. Frequently this is outside the range of possibility, and therefore the constant term should not be interpreted.

Page 42: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

The Error Term

Error term (e) = random, included because we do not expect a perfect relationship.

Sources of error1. Omitted variables2. Measurement error3. Incorrect functional form

Page 43: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Multivariate Analysis

Introducing the idea of ceteris paribus.

One cannot impose ceteris paribus unless all relevant variables are included in the model.

Page 44: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Coefficient of Determination

Coefficient of Determination – Percentage of Y-variation explained by the regression model.

Also referred to as R2

R2 = Variation Explained by Regression Total Variation in Y

R2 ranges from 0 to 1.

Page 45: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

TSS, ESS, RSS in words

Total Sum of Squares = TSS = How much variation there is to explain.

Explained Sum of Squares = ESS = How much variation you explained.

Residual Sum of Squares = RSS = How much variation you did not explain.

Page 46: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Adjusted R-Squared

Adding any independent variable will increase R2.

To combat this problem, we often report the adjusted R2.

Page 47: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

F Statistic

F-statistic tells us if the independent variables as a group explain a statistically significant share of the variation in the dependent variable.

Page 48: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Judging the significance of a variable

The t-statistic: estimated coefficient / standard deviation of the coefficient.

The t-statistic is used to test the null hypothesis (H0) that the coefficient is equal to zero. The alternative hypothesis (HA) is that the coefficient is different than zero.

Rule of thumb: if t>2 we believe the coefficient is statistically different from zero. WHY?

Understand the difference between statistical significance and economic significance.

Page 49: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Multicollinearity Multicollinearity - more than two

independent variables exhibit a linear correlation.

Consequences

a. Standard errors will rise, t-stats will fall

b. Estimates will be sensitive to changes in specification

c. Overall fit of regression will be unaffected

Page 50: ECONOMICS AND ELECTING THE PRESIDENT. THE WORK OF RAY FAIR

Other Econometric Issues

Omitted Variable Bias: You cannot impose ceteris paribus if relevant independent variables are not included in the model.

Small Sample Bias: You cannot adequately assess a relationship with an inadequate sample. Remember, we are trying to learn about the underlying population.

THE BIG WORDS: Heteroskedasticity and Autocorrelation