The Sashelp.Gas data set contains data from an experiment about gasoline engine exhaust emissions (Brinkman 1981). Nitrogen oxide emissions from a single-cylinder engine are measured for various combinations of fuel, compression ratio, and equivalence ratio. This data set is used to illustrate how to fit models by using nonlinearly transformed data. The following steps display information about the Sashelp.Gas data set and create Figure 54:
title 'Exhaust Emissions Data';
proc contents data=sashelp.Gas varnum;
ods select position;
run;
title 'The First Five Observations Out of 171';
proc print data=sashelp.Gas(obs=5);
run;
title 'The Fuel Type Variable';
proc freq data=sashelp.Gas;
tables fuel;
run;
Figure 54: Exhaust Emissions Data
| Exhaust Emissions Data |
| Variables in Creation Order | ||||
|---|---|---|---|---|
| # | Variable | Type | Len | Label |
| 1 | Fuel | Char | 8 | |
| 2 | CpRatio | Num | 8 | Compression Ratio |
| 3 | EqRatio | Num | 8 | Equivalence Ratio |
| 4 | NOx | Num | 8 | Nitrogen Oxide |
| The First Five Observations Out of 171 |
| Obs | Fuel | CpRatio | EqRatio | NOx |
|---|---|---|---|---|
| 1 | Ethanol | 12 | 0.907 | 3.741 |
| 2 | Ethanol | 12 | 0.761 | 2.295 |
| 3 | Ethanol | 12 | 1.108 | 1.498 |
| 4 | Ethanol | 12 | 1.016 | 2.881 |
| 5 | Ethanol | 12 | 1.189 | 0.760 |
| The Fuel Type Variable |
| Fuel | Frequency | Percent | Cumulative Frequency |
Cumulative Percent |
|---|---|---|---|---|
| 82rongas | 9 | 5.26 | 9 | 5.26 |
| 94%Eth | 25 | 14.62 | 34 | 19.88 |
| Ethanol | 90 | 52.63 | 124 | 72.51 |
| Gasohol | 13 | 7.60 | 137 | 80.12 |
| Indolene | 22 | 12.87 | 159 | 92.98 |
| Methanol | 12 | 7.02 | 171 | 100.00 |