There has been a big jump in the Isle of Man’s inflation rate.

The Consumer Prices Index for May stands at 3.9 per cent.

In April it was 2.1 per cent.

It is at its highest since February 2012.

Petrol, sea travel and air travel have all gone up, with Liverpool and Manchester flights rising significantly.

Going out for a meal has also got more expensive.

The CPI is the government’s preferred measure of inflation.

Another is the Retail Prices Index, which now stands at 8.4 per cent.

But the RPI is still used for some calculations. For example, the water rates charge rise earlier this year was based on RPI inflation.

In April last year the government launched a public consultation to consider whether the Manx RPI should be abandoned as a measure and the CPI measure adopted, in line with the UK, where it has been used as the main measure of inflation since 2013.

The consultation document explained how inflation is calculated using a hypothetical ’basket’ of goods and commodities, and calculating their average cost from a range of shops and suppliers.

The goods used in each measure are different, with the RPI measure including mortgage interest and other housing expenses (excluded from the CPI) and the CPI including university fees, excluded from the RPI.

In addition, a different formula is used in the calculations for RPI compared with CPI, with the result that RPI figures are generally significantly higher.

A third measure of calculation, the RPI (Jevons) uses the RPI ’basket’ of items but uses the CPI formula (known as the Jevons formula) for its calculations. This is said to mitigate the uplift on the standard RPI figure.

The Cabinet Office recommendation based on the consultation responses was to retain the RPI measure alongside the CPI but also publish RPI(J) figures, starting last September, but no official policy has yet been adopted.