- by David Clark

In a press release from February 2022, the mayor is quoted, in part, as saying: “Following ten years of decline, the data shows we have turned the corner with an increase in the past five years. ...the City is trending in the right direction.”

This comment discloses a common error made by many people who do not (truly) understand statistics, the meaning of “trends”, and limitations of using short time frames. Forecasting needs longer periods, usually from 40 to 100 data points. i A census every five years is only two data points, although it reflects what happened  over five year so could be considered to be “five” data points.

If, as the mayor has stated, a trend can be established simply by looking at two censuses which cover only a five-year spread, then Owen Sound has “turned the corner” five times since 1971 and “stumbled” four times.

The press release also stated:” The 2016 Census showed a slight decrease in Owen Sound’s population from 2011”. Well, that 2016 slight decrease was actually 344 people and that “’vision of being “Where You Want to Live’” increase was only 271 people; a net loss of 73 people.

One cannot establish a “trend” over a very short period of five years. Between the two points of 2016 and 2021 there are in fact four years unaccounted for (2017, 2018, 2019, 2020, as no census was done) in which we do not know what the population change looked like. Was there even change or was there a sudden increase in one year?

Indeed, two of those census years (2011 and 2016) did have population declines. Over the last fifty years (from 1971), the city has seen four periods of population decline with a net gain of only 3,143 people., or an average of 628.6 people per decade, or 62.9 people per year. If we look at the population from 2011 to 2021 (ten-year period), there is a net loss of 141 people.

The following graphs illustrate population changes over the long-term, from 1871 to 2021. Owen Sound’s population more or less plateaued in 1991with a net population loss of 20 people since then; we have fewer people than in 1991, 2006, and 2011.

So where do those 271 align with the population cohorts? Well, in broad terms, the  cohort of those aged 65-years and older increased from 25% to 27.2%, and those aged 85-years and older increased from 5.2% to 5.3% (included in the 65+ group). The age groups of 0 to 14 and 15 to 64 years dropped. So the increase was not in the youth and typical working age groups, but in older people. This is illustrated in the following graphs. Note, the graph shown as a line graph would normally be shown as a bar graph. I have chosen the line graph format for ease of visualisation.

 It should be noted, too, that the average household size has dropped since 1996, from 2.4 to 2.1. This indicates the need for more housing because more people are living alone. The following graph shows an increase of 1-person households and corresponding decrease in 2-person and 5-person households. 

I suggest that Own Sound has not “turned the corner” on positive population growth, at least not that one can confidently forecast based on a single event. It is not responsible to predict such an event given such a short five-year time-frame and doing so is a mockery of good statistical analysis and research standards.

I guess it is good politics, though.

David Clark , MA, BA(Honours), BES, MAd(Diploma) is an Independent Researcher in Owen Sound