City Nature Challenge 2020: Greater Adelaide - Estimates and Predictions

In light of current events the organizers of the City Nature Challenge have decided to proceed with the challenge in April, removing the competition aspect, and emphasizing the collaborative aspects of recording and sharing nature.

This year over 250 cities around the globe are participating in the City Nature Challenge. The size of each city area covered by the challenge various greatly as does the size of the local population and the range of natural areas within, so it will be difficult to directly compare cities. The Australian cities participating also vary greatly with:

• Greater Sydney project covering approx. 4,500km² and covering a population of 5 million
• Geelong project covering approx. 4,500km² and with a population of 5 million in and around its boundary
• Greater Adelaide project covering approx. 9,000km² and covering a population of 1.5 million
• Redlands City project covering 537km² and with a population of 3 million in and around its boundary

This being the first year any Australian City has participated, there is no information to determine how many people will participate and how many observations they will upload. However looking at a few cities that participated in 2019, some estimates can be made if we make a few assumptions.

Calculations show that on average the top 1% of contributors (power users) for each city made around 23% of the observations, the next 9% of contributors (regular users) made 40% of the observations, and the remaining 90% of contributors (occasional/new users) made 37% of the observations. So no matter which group you fall into every observation counts.

An estimate of the total number of observations this year is going to be especially difficult considering current events, which will dramatically alter the way in which people participate. However we can look at observations per contributor data from cities in 2019 to give us some idea. Taking only those cities with more than 100 contributors the average observations per contributor ranges from 7 all the way up to 98, with a mean of 27.5 and standard deviation of 16.6.

(Data for this graph includes observations uploaded from the challenge days that were uploaded after the end of the challenge. Hence it may not match official data from the challenge)

• Although Cape Town achieved the highest number of observations, there were 7 other cities that each had a higher average observations per contributor, but each with far less overall contributors
• La Paz had 30% more contributors than Cape Town, but on average a lower number of observations per contributor
• San Francisco Bay Area had almost twice as many contributors as Cape Town, but the average observations per contributor was around 60% lower.

The take home message here is that to achieve great results in the City Nature Challenge a city needs BOTH large numbers of contributors and highly motivated contributors.

Examining the Challenge: Estimates and Predictions

So how many observations are likely from Australian Cities? Assuming we have contributors with motivation similar to other cities (based on 2019 data), the estimates are as follows:

• If we have 100 contributors there will be a 68% chance we will record between 1,086 and 4,405 observations
• If we have 200 contributors there will be a 68% chance we will record between 2,171 and 8,811 observations
• If we have 500 contributors there will be a 68% chance we will record between 5,428 and 22,027 observations
• If we have 1000 contributors there will be a 68% chance we will record between 10,856 and 44,055 observations
• If we have 2000 contributors there will be a 68% chance we will record between 21,713 and 88,110 observations

But how will this estimate be affected this year with so many potentially contributing observations entirely from their own properties? How many observations do you think you could make across four days entirely from your own property (excluding captive and cultivated species)?

• If we have 100 contributors each uploading 10 observations each day we will record 4,000 observations
• If we have 200 contributors each uploading 10 observations each day we will record 8,000 observations
• If we have 500 contributors each uploading 10 observations each day we will record 20,000 observations
• If we have 1,000 contributors each uploading 10 observations each day we will record 40,000 observations
• If we have 2,000 contributors each uploading 10 observations each day we will record 80,000 observations

So there is no need to travel far and wide. The above shows if you record just a few observations from your property each day, we can still reach a great number of observations. In the next post I'll detail how you can easily make several dozen observations a day from a typical suburban backyard.

It's worth noting there are quite a few assumptions, guesstimates, approximations and estimates in the above numbers, so take them with a grain of salt.

הועלה ב-מרץ 31, 2020 05:26 לפנה"צ על ידי cobaltducks