First, I'd like to preface the question that I am an electronics noob.
I am trying to read and analog signal from an MCP3008 connected on a breadboard connected to my RPi v3 with a Cobbler.
On the breadboard, I've only got the Cobbler and the MCP3008, no wiring supplying power from the Cobbler to the MCP3008. When I run the simpletest.py script (from https://learn.adafruit.com/raspberry-pi-analog-to-digital-converters/mcp3008), I get a value of 1023 for each input. Just to see the difference, when I disconnect the cable from the RPi to the Cobbler and rerun the script, I get 0 values for all the inputs.
I would expect to get 0 values when I am not powering the MCP3008 as well. Why would this happen?