Since 1990 the City of Chicago went from 2,786,000 people to 2,705,000 - a loss of 81,000 people in 25 years and a 3% loss. Since 1990 the metro area of Chicago went from 8,239,820 people to 9,504,753 in 2016 - an increase of 1,264,933 people in 25 years and a 116% increase
Blanket market stats are not relevant in large markets.
I look at things from a macro level - Even a zip code is too big of an area to be taking stats at face value
Take the 60618 zip code in Bell School District - it has one of the fastest declining populations in the city. Why? Because what once was an area with 70% of the housing stock being 2-4 units it is now less than 50% because developers are converting the 2-4 buildings to SFH and selling them to Cubs and Blackhawks players with kids who want to go to a top rated school. So there is a decline in population because the number of housing units is declining, thus limiting the supply and increasing price. Now there are less 2-4 units so supply is low and those prices are going up, but we have a surplus of SFH and prices are not increasing. Throw in condos and that is a whole different market.
Even in the same school district houses west of western sell for a few hundred thousand dollars less. Go north of irving park road in the same zip code is a different school district and a totally different market.
So I would not even use stats to look at home sales in this zip code, the condo, SFH, and 2-4 unit markets are completely different and looking at a "days on market" stat or "average home price" includes all of those could lead you to make an investing mistake.
The city center now is growing faster than ever, having gained an estimated 42,423 people from 2010-15. But the population of the non-lakefront South Side is dropping even quicker, falling about 50,000 in the same period. So you need to look at the areas specifically to understand what is going on.