Let's look at the graph and see if you see the same as I did:
The graph told me exactly when my girlfriend left the house and returned again.
Even worse.
I noticed some people even attach a map with their location to the data. That is a direct invitation to burglars.
Now please do not blame Thingspeak or any other IOT service you might be using for this. It is your own responsability what you publically publish online.
Read the complete story here:
http://lucstechblog.blogspot.nl/2017/02 ... vited.html
Luc