pressure sensor

i have a mpx2200a pressure sensor and would like to use it as a simple barometer. the pin out of the sensor is:

pin 1: gnd pin 2: vout+ pin 3: vin pin 4: vout-

can i use analogread for obtaining the voltage value returned at pin2 by connecting pin2 to analog pin0 and pin4 to gnd on the arduino. i have done this but don't seem to get the correct value.

well, i am pretty new at this and was going to use the sensor as a very simple barometer.

i would like to read the voltage coming from pin2 and use an equation to come up with the current barometric pressure. i guess i would need some sort of an op-amp to amplify the voltage huh?

what would i do with the vout- pin though, tie it to ground?

I'm imagining that the intent with this chip is to drive an instrumentation amp.

http://en.wikipedia.org/wiki/Instrumentation_amplifier

The Instrumentation amplifier's job is to take the 40 milli volt span between high and low pressure and make it meaningful. 0-40 milli volts is not a voltage that the arduino analog pin can make a lot of use out of.