Using Simple Linear Regression to Assess the Success of the Montreal Protocol in Reducing Atmospheric Chlorofluorocarbons

Figures & data

Table 1. Original and Revised Phase-Out Schedules for CFS in Developed Countries

	1987 Original Montreal Protocol	1990 London Montreal Protocol	1992 Copenhagen Montreal Protocol	1990 U.S. Clean Air Act Amendments	1994 European Community Schedule
1990	100%
1991	100%	100%		85%
1992	100%	100%		80%
1993	80%	80%		75%	50%
1994	80%	80%	25%	25%	15%
1995	80%	50%	25%	25%	0%
1996	80%	50%	0%	0%
1997	80%	15%
1998	80%	15%
1999	50%	15%
2000	50%	0%

Source: Alternative Fluorocarbons Environmental Acceptability Study: www.afeas.org/montreal_protocol.html

Table

Year	Month	CFC
1977	01	139.90
1977	02	139.50
1977	03	139.00
1977	04	134.10
1977	05	135.00
1977	06	143.40
1977	07	140.30
1977	08	142.60
1977	09	144.70
1977	10	144.20
1977	11	144.80
1977	12	145.70
1978	01	148.60
1978	02	144.80
1978	03	148.40

Figure 1. Monthly Atmospheric Concentrations of CFCs (parts per trillion) from January 1977 to September 2004

Figure 2. Worldwide Production of CFCs 1985–2004

Table 2. ANOVA Table for the Simple Linear Regression Models

Period	Source	Sums of Squares	df	Means Square	F	p
Before 1990	Model	203118.741	1	203118.741	35093	.000
	Error	874.001	151	5.788
After 1994	Model	3061.553	1	3061.553	−73.863	.000
	Error	63.973	114	.561

Table 3. Parameter Estimates for the Simple Linear Regression Models

Period	Parameter	Estimate	Standard Error	t	p
Before 1990	β10	−19064.219	102.825	−185.405	.000
	β11	9.712	.052	187.330
After 1994	β20	3929.678	49.626	79.185	.000
	β21	−1.833	.025	−73.863

Table 4. ANOVA Table for the Simultaneous Linear Regression Models

Model	Source	Sums of Squares	df	Means Square	F	p
Simultaneous	Model	206180.294	2	103090.147	262.611	.000
Two Lines	Error	937.974	265	392.559

Table 5. Parameter Estimates for the Simultaneous Linear Regression Models

Period	Parameter	Estimate	Standard Error	t	p
Simultaneous	β10	−19064.219	80.409	−237.091	.000
Two Lines	β11	9.712	.041	239.554	.000
	β20	3929.678	124.635	31.530	.000
	β21	−1.833	.062	−29.410	.000

Table

Int1	x1	Int2	x2
1.00	1977.00		.00	.00
1.00	1977.08		.00	.00
1.00	1977.17		.00	.00
1.00	1977.25		.00	.00
1.00	1977.33		.00	.00
1.00	1977.42		.00	.00
.
.
.
1.00	1989.58		.00	.00
1.00	1989.67		.00	.00
1.00	1989.75		.00	.00
1.00	1989.83		.00	.00
1.00	1989.92		.00	.00
.00	.00	1.00	1995.00
.00	.00	1.00	1995.08
.00	.00	1.00	1995.17
.00	.00	1.00	1995.25
.00	.00	1.00	1995.33
.
.
.
.00	.00	1.00	2004.33
.00	.00	1.00	2004.42
.00	.00	1.00	2004.50
.00	.00	1.00	2004.58
.00	.00	1.00	2004.67

Figure 3. Comparing Predicted Levels of Atmospheric Concentrations of CFCs (parts per trillion) Using the Pre-Montreal Protocol and the Post Montreal Protocol Data

Figure 4. Residual Values for the Simple Linear Model fit to Pre-Montreal Protocol Data

Figure 5. Residual Values for the Simple Linear Model fit to Post-Montreal Protocol Data

Table 6. ANOVA Table for the Simple Linear Regression Models

Period	Source	Sums of Squares	df	Means Square	F	p
Before 1990	Model	203437.656	2	101718.828	27487.316	.000
	Linear	203118.741	1	203118.741
	Quadratic	318.915	1	318.915
	Error	555.086	150	3.70057333
After 1994	Model	3119.199	2	1559.5995	5086.140	.000
	Linear	3090.876	1	3090.876
	Quadratic	28.323	1	28.323
	Error	34.650	113	0.30663717

Table 7. Parameter Estimates for the Simple Linear Regression Models

Period	Parameter	Estimate	Standard Error	t	p
Before 1990	β10	427555.191	48109.963	8.887	.000
	β11	−440.634	48.511	−9.083	.000
	β12	.114	.012	9.283	.000
After 1994	β20	−280061.630	29041.620	−9.643	.000
	β21	282.180	282.180	29.044	.000
	β22	−.071	−.071	.007	.000