I had this task to explain to someone who understood maths, but was not a statistician what is "sums of squares". I was free to use graphs to aide him. So I begun.
The figure above gives a good approximation of how I explained. I drew a two dimensional plane with observations where the horizontal component was made to depend on the horizontal component. I even used the lines to show that it was actually a summation of the squares of deviation from the expected value.
The other guy apparently could not make out well what the expected value is, and was not comfortable with my using the regression model with a line of best fit to explain it.
A friend was standing nearby. I will soon reply with how he responded since it was not me. A challenge to you upcoming statistician like me, how would you have explained it without using the jargon that someone heard of over 10 years ago while in school?
The response will explain more on my title which is not captured here in this post.
Thanks for following.