Date of origination: August 10, 1995
Collected by Paul Martin
Last modified: 9/20/95 by PSM
		4/1/96 by PSM updated description

Description:  Environmental issues have consumed the attention of the United States in the 1980s and 1990s.  Questions abound over deforestation, global warming, green house effects, and the general effect of humans on the earth.  One serious question plaguing human kind is what determines these problems?  Are there single factors, multiple factors?  These data are of air pollution levels in 41 cities in the US.  There are a number of likely suspects that may account for pollution levels.  Your job is to investigate the causes of the annual mean concentration of Sulfer Dioxide, otherwise known as SO2 a primary component for acid rain. 

Source: Hand, D.J., F. Daly, A.D. Lunn, K.J. McConway and E. Ostrowski (1994)
	A Handbook of Small Data Sets.  London:  Chapman & Hall. p 20.

Number of observations: 41

Variables: There are 8 variables.

1.  city "City"
2.  so2 "Sulpher dioxide content of air in micrograms pwer cubic meter"
3.  temp "Average annual temperature in Farenheight"
4.  manuf "Number of manufacturing enterprises employing 20 or more workers"
5.  pop "Population size in 1970 census (thousands)"
6.  wind "Average wind speeds in mph"
7.  inches "Average annual precipitation in inches"
8.  days "Average number of days with precipitation per year"



First three observations from AIR.DAT
Phoenix 	10	70.3	213	582	 6.0   7.05	36
Little_Rock 	13	61.0	91	132	 8.2	48.52	100
San_Francisco   12	56.7	453   716  8.7	20.66   67

Last three observations from AIR.DAT
Seatle 	29	51.1	379	531	 9.4	38.79	164
Charleston 	31	55.2	35     71	 6.5	40.75	148
Milwaukee 	 16	    45.7    569   717 11.8  29.07	 123