### 1

**Assessing	the	Effect	of	Five	Gasoline	Properties	on	Exhaust	Emissions	from	Light******

**Duty	Vehicles	certified	to	Tier -**  **2	Standards Analysis**  **of	Data	from	EPA	Phase	3 (EPAct/V2/E**  **- 89)**  

## Appendix **I.2f Final	Model	Fitting**  **Non -**  **Methane	Organic	Gases (**  **NM O**  **G )	(**  **Bag	3 )** 

No. Observations: 837 No. Vehicles: 15 No. censored measurements: 119 No. missing measurements: 0 No. measurements removed: 0 Model Ty pe: Tobit regression

### 2 **Models fit for NMOG**  **( Bag 3): (Grand Intercept not**  **fit by Tobit models).**  Model Term Notation Model Full FM4 1 

### FM5 FM6 FM7 FM8 FM9 FM10 etOH Z

e ● ● ● ● ● ● ● ● 

### Arom Z

a ● ● ● ● ● ● ● 

### × RVP Z

r ● ● ● ● ● ● ● ● 

### T50 Z

5 ● ● ● ● ● ● ● ● 

### T90 Z

9 ● ● ● ● ● ● ● ● 

### etOH × etOH ZZ ee ● 

### × T50 × T50 ZZ 55 ● ● ● ● 

### × etOH × Arom ZZ ea ● ● 

### × etOH × RVP ZZ er ● ● ● ● ● ● ● ● 

### etOH × T50 ZZ e5 ● ● ● ● ● ● ● ● 

### etOH × T90 ZZ e9 ● 

### × Arom × RVP ZZ ar ● ● ● ● ● 

### × Arom × T50 ZZ a5 ● 

### × Arom × T90 ZZ a9 ● ● ● 

### × T50 × T90 ZZ 59 ● 

### × RVP × T90 ZZ r9 ● ● ● ● ● ● 

### × 1 denotes “Full minus 4, etc. ”



### NMOG **( Bag 3**  **): Model fitting history, starting with the 16** **- t**  **erm extended**  **model.**



### Fit Parameters Test with respect to Previous Model 

### Model p - 1 1



### -2 ln L Dev. d Pr>χ 2 

### Full Model 16 2605.071 FM4 12 2605.748 0.677 4 0.954 FM5 11 2605.753 0.005 1 0.944 FM6 10 2606.328 0.575 1 0.448 FM7 9 2607.179 0.851 1 0.356 FM8 8 2607.668 0.489 1 0.484 FM9 7 2608.221 0.553 1 0.457 FM10 2 

### 6 2608.338 0.117 1 0.732

1 Total number of terms excludes the intercept, as the Tobit Models do not fit intercepts

. 2 Best fit with respect to the 16

-term extended model.

### 3

**NMOG (** **Bag 3 ):**  **Co efficients and Tests of Effect for the**  **Full and Reduced Models, with respect to**  **the 1 6** **- term**  **extended model (NOTE: model fitting with respect to the 11**  **- term design model gives**  **the same results).** 

### Effe ct Fu ll Model (Exte nded) Re duced Model (FM10) Es ti mate St d. E

rr. d. f. χ2

v al ue Pr>χ2 Es ti

mate St d.E

rr. d. f. χ2

v al ue Pr>χ2 In tercept -5.4889 1 Z e -0.0088 0. 0603 1 0. 0200 0.8841 0. 0339 0.0438 1 0. 60 0. 44 Z a -0.0158 0. 0378 1 0. 17 0.6757 1 Z r -0.0824 0. 0509 1 2. 62 0.1058 -0.0572 0.0384 1 2. 22 0. 14 Z 5 0.0207 0. 0672 1 0.090 0.7585 0. 0783 0.0466 1 2. 82 0. 093 Z 9 0.1406 0. 0391 1 12.9 0.0003 0. 1467 0.0345 1 18.1 <.0001 ZZ ee -0.0122 0. 0702 1 0.030 0. 862 ZZ 55 -0.0510 0. 0573 1 0. 79 0.3732 ZZ ea -0.0307 0. 0569 1 0. 29 0.5893 ZZ er 0.0804 0. 0386 1 4. 33 0.0374 0. 0707 0.0337 1 4. 4000 0. 036 ZZ e5 -0.0802 0. 0742 1 1. 17 0.2798 -0.0728 0.0344 1 4. 4800 0. 034 ZZ e9 0.0119 0. 0456 1 0.070 0.7934 ZZ ar -0.0601 0. 0615 1 0. 95 0.3285 ZZ a5 -0.0435 0. 0689 1 0. 40 0.5279 ZZ a9 -0.0303 0. 0386 1 0. 62 0.4319 ZZ 59 0.0256 0. 0514 1 0. 25 0.6182 ZZ r9 0.0521 0. 0435 1 1. 43 0.2313 4.49892

1.0095 1. 0109 1 N ot fit by t he

T obit model; calculat edas mean of intercep ts for i

ndividual vehicles

. 2N ot fit by T obit model; calculat ed as va riance of intercep ts for i

ndividual vehicles

. 2 veh 

###  2  

### 