More info on Octopus's analysis of Tease and Squeeze

Data sources

The data came from price comparison websites, collective switch data from industry consultants, and suppliers’ own websites. We also called suppliers to confirm data and fill gaps where we could.

Data gathering process

On a daily basis throughout the 6 month period we collected all open market data into a database. We manually added in exclusive and collective deals as they arose. We then collected all SVTs from the market and called suppliers for this information where it wasn't publicly available.

Regionality

We used data for the Eastern region only. We spent some time analysing data for the country as a whole, but we found that averages were hiding the picture, plus some offers really varied by region – and customers only live in one region, they buy a specific deal not a national average one. We chose Eastern because it’s one of the largest and most competitive. The amount of data ran into tens of thousands of data points for this region alone.

Companies in the analysis

We included all companies we could identify with multiple deals including a discoverable SVT.

Time frame

For cheapest deals, we looked at the cheapest deals offered by each supplier over the 6 months from March to September. This was because many deals only apply for a short term so wouldn’t show in a daily snapshot.

For the SVT we used the current SVT because this is the closest representation to what the customer will be paying when the deal finishes. Notably, SVTs hadn’t moved much over this period.

Where we make projections beyond the fixed terms we use the current (latest) SVT for the relevant supplier.

Deals shown

We only looked at monthly direct debit deals as this is most prevalent in deals and directly comparable across suppliers’ SVTs. We assessed the picture for a dual fuel, non-economy 7 customer with Ofgem’s medium typical consumption of 3,100 kWh of electricity and 12,500 kWh of gas. For each company we found their cheapest deal available and their current SVT.

Detailed data

The total data set runs to tens of thousands of rows. Please contact us on hello@octopus.energy if you'd like it all.

The tables below list most of the data quoted in the interviews on BBC Radio 4's Money Box programme. The data has been extensively checked, but with the complexity of analysis errors may arise. Any brought to our attention will be fixed and corrections published immediately.

Prices as they stood on September 9, 2016 showing current cheapest tariff for each supplier alongside SVT and multiyear projections:
https://octoenergy-production-statics.s3.amazonaws.com/charts/eastern_prices_20160909.pdf

Cheapest SVT for each supplier in past 6 months alongside current SVT and current and projected rankings:

https://octoenergy-production-statics.s3.amazonaws.com/charts/tariffs_last6months_rates_20160909.pdf