### 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 **N .3** 

**Model	Fitting	Information	for** 

# Ethan **ol (** **Bag	1 )** 

This appendix summarizes model fitting for Bag- 1 Ethanol
. Model
-fitting techniques and approaches summarized in Section 8 .7 . Features of the data and modeling for this compound are listed below. Fuel
-parameter matrix: FULL Media contamination: YES No. measurements: 913 No. censored values: 193 Modeling approach: TOBIT REGRESSION Estimated Dependent Variable model: YES

### 2 **Models fit for Ethanol** **, Bag 1 (all models include an intercept term)** Model Term Notation Model Full FM6 FM9 FM 10 FM 11 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 × T50 ZZ e5 ● 

### × etOH × T90 ZZ e9 ● 

### × etOH × RVP ZZ er ● 

### × Arom × T50 ZZ a5 ● ● 

### × Arom × T90 ZZ a9 ● 

### × T90 × T90 ZZ 99 ● ● ● 

### × T50 × T90 ZZ 59 ● ● ● ● 

### × Arom × RVP ZZ ar ● ● 

### × RVP × T90 ZZ r9 ● 

### × 

### Model Fitting History for **Ethanol , Bag 1 (** **FM 11**  **selected as best -** **fit model).** 

## Fit Parameters Test with respect to Full Test with respect to Previous Model 

### Model p -2ln

L BIC 1 

### Dev. 1 

### d Pr>χ 2 

### Dev. d Pr>χ 2 

### Full 18 632.42 750.84 FM6 12 633.33 712.28 0.9125 6 0.99 FM9 9 634.97 694.18 2.5494 9 0.98 1.6369 3 0.65 FM 10 8 635.10 687.74 2.6863 10 0.99 0.1369 1 0.71 FM 11 7 637.88 683.93 5.4581 11 0.91 2.7719 1 0.095 1 A lower value indicates a better fit. 1 The deviation is the difference in the
-2loglik statistics for the nested and reference models, respectively, per 

### Error! Reference source not **found.**

.

### 3 **Coefficients and Tests of Effect for the**  **Full and Best** **- Fit Models** 

**– Ethanol**  **(Bag 1).** Effect Full Model Best
-Fit Model ( FM 11 ) Estimate Std.Err. d.f. tvalue Pr>t Estimate Std.Err. d.f. tvalue Pr>t 

### Intercept 1 15
-4.9081 

### Z e 1.4759 0.07240 15 20.38 <0.00001 1.4643 0.07115 15 20.56 <0.00001 

### Z a -0.0067 0.04327 15
-0.16 0.88 

### Z r -0.05004 0.04316 15
- 1.16 0.26
-0.05990 0.02940 15
-2.06 0.057 

### Z 5 0.1050 0.03806 15 2.76 0.015 0.07188 0.02964 15 2.37 0.032 

### Z 9 -0.1261 0.03701 15
- 3.47 0.0034
-0.09990 0.03574 15
-2.78 0.014 

### ZZ ee -0.4787 0.06014 15
- 7.96 <0.00001
-0.4967 0.05229 15
- 9.51 <0.00001 

### ZZ 55 0.1261 0.05018 15 2.51 0.024 0.1121 0.03826 15 2.90 0.011 

### ZZ ea -0.005952 0.03881 15
-0.15 0.88 

### ZZ e5 0.02820 0.05277 15 0.54 0.60 

### ZZ e9 0.0008509 0.06491 15 0.0090 0.99 

### ZZ er 0.03237 0.05103 15 0.64 0.53 

### ZZ a5 0.03318 0.03212 15 1.04 0.32 

### ZZ a9 -0.01143 0.03461 15
-0.33 0.74 

### ZZ 99 -0.5112 0.04523 15
- 1.13 0.28 

### ZZ 59 0.05311 0.04341 15 1.22 0.24 

### ZZ ar 0.04136 0.02855 15 1.45 0.17 

### ZZ r9 -0.008676 0.04644 15
-0.20 0.85 2 veh 

##  1 0.1283 2  

##  0.5697 0.05739 1 Not fit by the model, but manually recalculated from intercepts for individual vehicles.

### 4

**Coefficients for Models ( FM** **11) for individual Jackknife replicates used to calculate standard errors for**  **model terms.**