Sometimes it can feel like change will never come. That no matter how loud your voice is, it's not being heard.

There have been many protests for Black Lives Matter in the past that have yet to yield the change we need. The protests in 2017 over the murder of Philando Castile. Protests when the officer who murdered 12-year-old Tamir Rice was not convicted in 2015. And there are far too many more examples.

There is some hope. Evidence suggests that social change off the back of a protest or movement can be boiled down to a number. A percentage to be more specific.

Harvard University political scientist Erica Chenoweth found that 3.5 per cent is the magic number. It tends to determine whether a protest will be successful at initiating change. That is, if 3.5 per cent of a population takes to the streets in protest, the protest will be successful.

I discovered this interesting piece of research on Tik Tok of all places. Planet Money shared a video which boiled down the facts. It explained that in the last 100 years, every movement that hit the 3.5 per cent number has been successful. The video showed examples of public demonstrations that successfully yielded change: People Power Revolution in the Philippines had 3.6 per cent and the Rose Revolution in Georgia 4.7 per cent and Estonia's Singing revolution had 19 per cent.

Chenoweth's deduced this figure by looking at historical data and news reports. She evaluated the number of people visible in a form of protest - striking, marching or sitting in. Predictably, the data showed the more participants, the better chance of success. But it also showed that when participation in a demonstration reaches 3.5 per cent, the likelihood of meaningful change became seemingly inevitable.

One of the other interesting aspects to Chenoweth's research is that non-violent demonstrations seem to be more effective than violent ones. She found that major nonviolent initiatives are successful 53 per cent of the time, while violent campaigns are only successful at a rate of 26 per cent.

It interesting stuff and sends a message of hope.

For all those that took to the streets to march for change, just know, your voices are being heard. And if enough of us get involved, change will come.