The value of Dot Dot Dot’s social impact over the past 10 years: How we calculated it

In June, Dot Dot Dot celebrated its 10th birthday, and August marked a decade since we housed our first guardian.

We’ve worked out the total value of our guardians’ volunteering over the past 10 years is £4.3m and the value of the impact Dot Dot Dot has made is £1.8m. These two figures make us very proud, but how did we get to them?

The value of all our guardians’ volunteering

In the 10 years up to June 2021, our guardians volunteered a total of 339,058 hours, and 77.7% of those hours were volunteered by guardians living in London.

We use the National and London Living Wages as the basis for calculating the value of each hour volunteered. Aside from the fact it’s good practice and Dot Dot Dot is a Living Wage Employer, those wages are equivalent to that paid for entry-level roles in charities, and we think it’s reasonable to assume a majority of our guardians are undertaking work of at least this value.

If our guardians were working and not volunteering for free, then their employers would be paying costs associated with employing people e.g. National Insurance, pension, sick pay contributions, and a good rule of thumb is that these add a further 30% to a salary. So, we:

1. Broke down all our volunteering by the year in which it occurred
2. Assumed in each of those years 77.7% of the volunteering was done in London
3. Worked out the London and National Living Wage rates plus 30% on-costs for each year
4. Calculated an hourly wage for both London and non-London based volunteering weighted across the 10 years we were looking at.
5. Multiplied those weighted hourly wages by the number of hours volunteered in and out of London over 10 years

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Value of London volunteering (263.448 x £13.09) + Value of out-of-London volunteering (75,610 x £11.31) = Value of all Dot Dot Dot guardians’ volunteering: £4.3m

Working out our social impact

We are very proud that the total value of our guardians’ volunteering was £4.3m over the past decade. However, we really wanted to understand the impact that Dot Dot Dot had made in 10 years i.e. what was the value of the volunteering that only happened because guardians were housed by us.

To do this we needed to get some data from our historic and current guardians to calculate:

Hours volunteered x monetary value of those hours x %age of volunteering at Dot Dot Dot which was/is additional to any they did before being housed by us x %age of volunteering at Dot Dot Dot which was/is attributable to being housed by Dot Dot Dot

To make this as robust as possible we needed data from a representative sample of guardians – we needed to be confident that not just the people who volunteered a high number of hours had responded. So:

1. We asked all current guardians to tell us how many hours they volunteered in the the couple of months before joining Dot Dot Dot – in order to compare the difference between the hours they now volunteer
2. We also asked them how important a factor being housed by Dot Dot Dot was in any extra volunteering they did
3. We asked all former guardians the same two questions

We compared the average hours volunteered by current guardians with those of former guardians, and found them to be very similar, within a couple of percentage points. Fundamentally, we were confident in the representativeness of our sample.

Now we needed to look at the additionality and attribution points, and calculated that:

• 66.85% of volunteering was additional
• 62% of that additional volunteering was due to people being housed by Dot Dot Dot

We received replies from enough people to give us a strong confidence level of 95% with a confidence interval of 5.5% in their answers. So, for example, for the numbers above, we were 95% confident that, if every guardian had responded to our survey, then between 61.35% and 72.35% (66.85% ± 5.5%) of their volunteering was additional.

Which meant we could do our calculation, and found the value of the impact Dot Dot Dot has made in support of charitable causes in its 10-year history is £1.8m.

Read more about the value of our social impact over the past 10 years.