Application of the Limited Enthusiasm Model with Reversion, Written in 2022.
Newfrontiers is a UK protestant church founded by Terry Virgo in the 1970s. It is charismatic in style and has been a significant part of the movement in the UK seeking to restore churches to a true Biblical pattern. In 2011, Terry Virgo handed the church leadership over to eleven “apostolic leaders”, each with their own “sphere”. It has grown continually since its inception. This analysis investigates how the church is experiencing revival growth and forecasts its potential future numbers.
Estimating Model Parameters
I will use the Newfrontiers’ membership data to estimate the parameters of the Limited Enthusiasm Model with Reversion. Using this cut-down version of the Demographics Model avoids estimating values for child retention among church members, hardening rates etc. There is no information about these values for the Newfrontiers. The reversion model has only five parameters:
- Reproduction Potential
- Duration Enthusiastic
- Loss Rate
- Fraction of Converts who Become Enthusiasts
- Initial Fraction of Enthusiasts in the Church
The key parameter is the reproduction potential. Its value will determine if the Newfrontiers has revival growth.
Calibration Strategy
The best fit between data and model is found using least squares. To help find the most suitable parameter values, I vary parameters 3-5 above and optimise for 1-2, the reproduction potential and duration enthusiastic. Out of this optimisation set, I determined optimistic scenarios – those with moderate growth, and pessimistic scenarios – those with lower growth. I chose a representative of each optimisation close to the group’s average. I excluded extreme values of the parameters as they are unlikely to be correct.
Membership 2000–2020
I took the data from Brierley’s church statistics.
Every optimisation indicates that Newfrontiers is experiencing revival growth with no sign of slowing down.
One such optimisation is given in figure 1. The reproduction potential chosen was an average of the optimistic scenarios, a value of 1.072. A typical pessimistic value is 1.003. The data fit in figure 1 is identical for both scenarios, which means I cannot choose between the scenarios on this data alone.
For all scenarios, the reproduction potentials are well above the revival threshold of 1.00 as of 2020. Thus, whatever data fit is used, Newfrontiers should continue to have revival growth for the foreseeable future, provided it keeps the same reproduction potential. “Revival growth” is where church and enthusiast numbers have accelerated growth.
Range of Optimised Parameters
The optimisations indicate a range of possible parameter values:
| Reproduction Potential | 1.002-1.189 |
| Duration Enthusiastic | 0.1–11 years |
| Loss Rate (Reversion and Deaths) | 2%–6% |
| Fraction of Converts who Become Enthusiasts | 10%–50% |
| Initial Fraction of Enthusiasts in the Church | 0.5%–7% |
Although there is a wide range of parameter values above, these do not affect the revival growth status of the church. I assumed the church could potentially contact the whole UK population in these simulations. If I reduced the contactable population to only 15% of the GB population, I obtained similar ranges for the parameters.
Future Projections
In Figure 2, I have extended simulations to the year 2100. Although these simulations are not predictions, the graph indicates possible futures, a range of forecasts, assuming the church reproduces enthusiasts at the same rate.
There is little to choose between the simulations up to 2040. The most pessimistic scenario has the church’s growth slowing in the second half of the century. Most scenarios show the church’s growth continuing to accelerate. The most optimistic simulation indicates church growth of six times its current numbers by the end of the century.