An Analysis of the 2002 Presidential Elections Using Logistic Regression

Nicolau, Jairo

doi:10.1590/1981-3826200700010006

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Research Notes • Bras. Political Sci. Rev. 1 (1) • 2007 • https://doi.org/10.1590/1981-3826200700010006 copy

An Analysis of the 2002 Presidential Elections Using Logistic Regression^* * Editors’ Note: The need to speed up the launch of the first issue of BPSR, which had already been delayed several times, regrettably led the Editors to overlook their duty to inform two contributors of the overlap between their respective pieces. This explains the publication of this Research Note by Jairo Nicolau, in which he sets out to analyse the 2002 Brazilian presidential election by means of the technique of logistic regression, claiming that although this technique is widely used for election studies in other countries, it had been little used in Brazil to date, and of the article by Yan de Souza Carreirão (Relevant Factors for the Voting Decision in the 2002 Presidential Election), in which he investigates this same election by testing some of the main hypotheses about electoral behaviour in the country by means of logistic regression analyses.

Authorship SCIMAGO INSTITUTIONS RANKINGS

The 2002 elections were a watershed in Brazilian electoral history. Three aspects of the process in particular have been amply stressed in several analyses. The first is the symbolic dimension of Lula's personal victory, the biography of a man of the people who rises to the country's most important office. The second is the victory of PT, the main leftwing party in the country, winning federal office 22 years after being founded. The third is the dimension of the victory, with the president obtaining a resounding vote (61% of the valid votes), which surpassed that of any other Brazilian president since 1945. Despite this, the efforts made by political science to analyse the 2002 elections remain limited, in particular regarding the use of opinion poll results.

		Log-odds	Significance	Odds Ratio	95% Confidence Interval for the Odds Ratio
Age (16-24)
	25-34	-0,06	0,780	0,94	0,63-1,42
	35-44	0,20	0,365	1,22	0,79-1,87
	45-59	0,81	0,000	2,25	1,46-3,47
	60+	0,73	0,005	2,07	1,25-3,42
Sex (Female)
	Male	-0,36	0,009	0,70	0,53-0,92
Colour (Non-White)
	White	0,34	0,014	1,41	1,07-1,86
Schooling (Up to 4th Grade)
	5 th to 8 th	0,24	0,195	1,27	0,88-1,83
	9th to 11th	0,49	0,014	1,64	1,11-2,42
	Higher	0,65	0,015	1,91	1,14-3,21
Religion (Catholic)
	Others	-0,00	0,989	0,99	0,63-1,57
	Evangelical	0,04	0,834	1,04	0,70-1,57
Evaluation of FHC Government (Negative)
	Positive	1,17	0,000	3,21	2,40-4,29
Party Sympathy (None)
	PT	-2,08	0,000	0,13	0,08-0,21
	PMDB	0,53	0,028	1,70	1,06-2,74
	PSDB	1,45	0,000	4,25	2,29-7,87
	Others	0,47	0,069	1,59	0,96-2,64
Left-Right Position (None)
	Left	-0,76	0,001	0,47	0,30-0,74
	Centre	-0,13	0,528	0,88	0,59-1,32
	Right	0,63	0,001	1,88	1,28-2,75
Constant		- 1,90	0,000

		Log-odds	Significance	Odds Ratio	95% Confidence Interval for the Odds Ratio
Age (16-24)
	25-34	-0,30	0,229	0,74	0,45-1,21
	35-44	-0,44	0,113	0,65	0,38-1,11
	45-59	-0,17	0,547	0,84	0,48-1,48
	60+	0,07	0,827	1,07	0,56-2,04
Sex (Female)
	Male	-0,37	0,041	0,69	0,49-0,99
Colour (Non-White)
	White	0,23	0,199	1,26	0,89-1,80
Schooling (Up to 4th Grade)
	5 th to 8 th	0,26	0,269	1,30	0,82-2,06
	9th to 11th	0,45	0,080	1,57	0,95-2,60
	Higher	0,02	0,955	1,02	0,48-2,18
Religion (Catholic)
	Others	2,45	0,000	11,5	7,87-16,91
	Evangelical	0,13	0,698	1,14	0,59-2,23
Evaluation of FHC Government (Negative)
	Positive	0,23	0,207
Party Sympathy (None)
	PT	-1,41	0,000	0,24	0,15-0,41
	PMDB	-0,45	0,300	0,64	0,28-1,49
	PSDB	-0,36	0,510	0,70	0,24-2,05
	Others	0,95	0,002	2,59	1,42-4,71
Left-Right Position (None)
	Left	-0,59	0,041	0,55	0,32-0,98
	Centre	-,016	0,534	0,85	0,51-1,42
	Right	0,303	0,243	1,35	0,81-2,25
Constant		-0,203	0,000

		Log-odds	Significance	Odds Ratio	95% Confidence Interval for the Odds Ratio
Age (16-24)
	25-34	0,47	0,090	1,59	0,93-2,74
	35-44	0,68	0,018	1,97	1,12-3,47
	45-59	0,58	0,067	1,79	0,96-3,33
	60+	0,82	0,023	2,26	1,18-4,57
Sex (Female)
	Male	-0,19	0,310	0,83	0,58- 1,19
Colour (Non-White)
	White	0,243	0,197	1,28	0,88-1,85
Schooling (Up to 4th Grade)
	5 th to 8 th	0,09	0,743	1,09	0,66-1,81
	9th to 11th	0,86	0,001	2,36	1,43-3,99
	Higher	1,03	0,002	2,79	1,45-5,37
Religion (Catholic)
	Others	0,08	0,774	1,08	0,62-1,88
	Evangelical	-0,70	0,047	0,49	0,25-0,99
Evaluation of FHC Government (Negative)
	Positive	0,25	0,405	1,29	0,89-1,86
Party Sympathy (None)
	PT	0,82	0,023	0,89	0,04-0,18
	PMDB	0,47	0,090	0,75	0,35-1,63
	PSDB	0,68	0,061	1,66	0,67-4,08
	Others	0,58	0,067	1,78	0,98-3,24
Left-Right Position (None)
	Left	-0,25	0,405	0,78	0,43-1,41
	Centre	0,28	0,306	1,32	0,78-2,24
	Right	0,28	0,318	1,32	0,76-2,29
Constant		-2031	0,000

		Log-odds	Significance	Odds Ratio	95% Confidence Interval for the Odds Ratio
Age (16-24)			0,019
	25-34	0,09	0,642	1,09	0,78-1,57
	35-44	0,06	0,779	1,06	0,72-1,57
	45-59	0,56	0,006	1,75	1,78-2,60
	60+	0,50	0,031	1,65	1,05-2,61
Sex (Female)
	Male	-0,19	0,135	0,83	0,65-1,06
Colour (Non-White)
	White	0,27	0,036	1,31	1,01-1,68
Schooling (Up to 4th Grade)			0,021
	5 th to 8 th	0,15	0,382	1,17	0,83-1,62
	9th to 11th	0,51	0,004	1,67	1,18-2,37
	Higher	0,46	0,059	1,58	0,98-2,53
Religion (Catholic)			0,838
	Evangelical	0,02	0,894	1,02	0,74-1,41
	Others	-0,12	0,581	0,89	0,58-1,36
Evaluation of FHC Government (Negative)			0,000
	Positive	1,04	0,000	2,82	2,17-3,66
Party Sympathy (None)			0,000
	PT	-1,99	0,000	0,14	0,08-0,22
	PMDB	0,34	0,131	1,40	0,91-2,17
	PSDB	1,27	0,000	3,58	2,10-6,08
	Others	0,31	0,149	1,37	0,89-2,09
Left-Right Position (None)			0,000
	Left	-0,80	0,000	0,45	0,29-0,69
	Centre	0,02	0,933	1,02	0,70-1,47
	Right	0,78	0,000	2,19	1,55-3,10
*Constant*			0,000

		Lula	Serra	Garotinho	Ciro	Blank/Spoilt
Age
	16-24	57	19	13	6	5
	25-34	57	18	9	9	7
	35-44	54	19	9	10	8
	45-59	47	30	10	8	5
	60+	45	29	12	8	7
	Cramer's V = 0,08; p<0,0001
Sex
	Male	58	20	8	8	6
	Female	49	24	12	9	6
	Cramer's V = 0,01; p<0,0001
Schooling
	Illiterate/Up to 4th grade	54	23	11	7	5
	5th to 8th	56	20	11	7	6
	9th to 11th	50	22	10	11	7
	Higher	48	28	7	12	4
	Cramer's V = 0,06; p = 0,06
Self-Defined Colour
	White	48	26	11	10	6
	Non-White	58	18	10	7	6
	Cramer's V = 0,12; p<0,0001
Religion
	Catholic	57	24	5	9	5
	Pentecostal Evangelical	32	16	44	3	6
	Non-Pentecostal Evangelical	44	20	24	5	7
	Others	56	19	5	9	11
	Cramer's V = 0,42; p<0,0001
Evaluation of Fernando Henrique Government
	Positive (Excellent, Good, Positive Average)	43	33	10	9	5
	Negative (Terrible, Bad, Negative Average)	64	11	11	8	7
	Cramer's V = 0,28; p<0,0001
Party Sympathy
	PT	86	4	5	2	3
	PMDB	38	45	7	8	3
	PSDB	20	63	6	10	1
	Others	35	31	19	14	1
	None	45	24	13	10	8
	Cramer's V = 0,23; p<0,0001
Position on the Left-Right Spectrum
	Left	74	9	7	6	5
	Centre	49	20	11	11	8
	Right	39	38	12	9	3
	Doesn't know - Didn't Answer	48	22	13	8	9
	Cramer's V = 0,19; p<0,0001

		Lula	Serra	Blank/Spoilt
Age
	16-24	70	22	8
	25-34	71	23	6
	35-44	71	22	7
	45-59	62	30	8
	60+	61	30	9
	Cramer's V = 0,07; p = 0,02
Sex
	Male	71	23	7
	Female	65	27	8
	Cramer's V = 0,06; p = <0,03
Schooling
	Illiterate/Up to 4th grade	69	24	6
	5th to 8th	70	21	9
	9th to 11th	65	28	7
	Higher	63	31	7
	Cramer's V = 0,06; p = 0,05
Self-Defined Colour
	White	63	30	7
	Non-White	72	21	7
	Cramer's V = 0,27; p<0,0001
	Religion
	Catholic	69	26	6
	Pentecostal Evangelical	62	29	9
	Non-Pentecostal Evangelical	60	24	16
	Others	70	19	11
	Cramer's V = 0,09; p<0,0001
Evaluation of Fernando Henrique Government
	Positive (Excellent, Good, Positive Average)	57	36	7
	Negative (Terrible, Bad, Negative Average)	80	13	8
	Cramer's V = 0,27; p<0,0001
Party Sympathy
	PT	92	4	4
	PMDB	52	44	4
	PSDB	30	66	5
	Others	56	40	4
	None	63	28	10
	Cramer's V = 0,26; p<0,0001
Position on the Left-Right Spectrum
	Left	87	8	5
	Centre	67	24	9
	Right	51	44	6
	Doesn't know - Didn't Answer	65	24	11
	Cramer's V = 0,23; p<0000,1

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[1] *
Editors’ Note: The need to speed up the launch of the first issue of BPSR, which had already been delayed several times, regrettably led the Editors to overlook their duty to inform two contributors of the overlap between their respective pieces. This explains the publication of this Research Note by Jairo Nicolau, in which he sets out to analyse the 2002 Brazilian presidential election by means of the technique of logistic regression, claiming that although this technique is widely used for election studies in other countries, it had been little used in Brazil to date, and of the article by Yan de Souza Carreirão (Relevant Factors for the Voting Decision in the 2002 Presidential Election), in which he investigates this same election by testing some of the main hypotheses about electoral behaviour in the country by means of logistic regression analyses.