• We have revised lower our GDP forecast for 2018 to just under 1.5 per cent mainly due to weak performance in the first quarter. But the slowdown is likely to be temporary.

• The Commentary in this Review builds a case for higher government spending. We have, as a result, allowed for higher total managed expenditure resulting in a somewhat slower fiscal adjustment than presently planned.

• Following the exchange rate depreciation of June 2016, annual consumer price inflation peaked at 3.1 per cent in November 2017 and is forecast to ease back to the target rate of 2 per cent over the next eight quarters.

• Because of the dip in economic performance we expect the timing of our next increase in Bank Rate to be delayed to August but reiterate that the MPC should remain on a gentle path of monetary policy normalisation.

• Last year the global economy expanded at its fastest pace since 2011. We continue to expect to see slightly faster global growth this year with momentum being carried forward. We expect growth to continue to be broadly based.

• With some advanced economies appearing to be operating at close to full capacity, a slowdown in the pace of expansion in the medium term is likely unless productivity growth picks up substantially. We retain our view that the medium term outlook is for growth of around 3.5 per cent a year.

• No economic outlook is without uncertainties. Issues such as increases in tariffs, the effect of the gradual removal of monetary accommodation and the prolonged persistence of low inflation, create potential for surprises to the forecast.

This paper introduces a special issue of the Review on how the National Institute Global Econometric Model (NiGEM) is being used to navigate uncertain times. NiGEM is the leading global macroeconomic model, used by both policy-makers and the private sector across the globe for economic forecasting, scenario building and stress testing. The paper summarises the main features of NiGEM and describes some standard model simulations to illustrate how the model responds to monetary, fiscal and technology shocks.

There is a strong case for boosting public investment in many countries based on identified country-specific structural weaknesses and the relatively low levels of such investment. This paper analyses the potential macroeconomic benefits of increased public investment using simulations on NiGEM. The results suggest that the supply-side benefits from raising potential output are likely to lead to more favourable macroeconomic outcomes than those from using many other standard fiscal instruments, although it takes many years for the full effect on potential output to accumulate. Variant model simulations also suggest that a fiscal stimulus will be more effective in the short term the less it is offset by monetary policy, making well-targeted policy initiatives especially effective when policy interest rates are at the zero lower bound. Globalisation implies that spillover effects from collective action are larger than in the past, boosting multipliers relative to the case where countries take individual action, particularly in the first two years after the policy change. Such spillovers are likely to be particularly important in small open European economies, especially those strongly integrated in European value chains.

For a large number of countries, we augment the specification of import demand in NiGEM by accounting for different import contents of individual expenditure components. Three examples illustrate that these changes have important implications for model outcomes. In the case of the recently enacted US tax reform and in a ‘hard landing’ scenario for China, spillovers become more pronounced while the domestic effects turn out more muted than in the default specification. The reverse is true for the ramifications of a public investment push in Germany. Hence, we believe that our add-on to NiGEM can be a useful tool for robustness exercises, in particular for spillover studies.

Exchange rate fluctuations have been particularly large since mid-2014, displaying divergent developments across the period. The nominal effective exchange rate of the dollar has appreciated by 15 per cent since June 2014, masking a 25 per cent appreciation to December 2016 followed by a depreciation of 8 per cent. Changes in the euro have turned positive after being negative. This article attempts to measure the impact of currency changes on domestic activity, accounting for the source of fluctuations. More specifically, by using the multi-country structural model NiGEM, we show that different types of exchange rate shocks can have different macroeconomic outcomes. Focusing on the period from January 2017 to February 2018, we show that the depreciation of the dollar, stemming mostly from changes in sentiment in foreign exchange markets, would in fact have been detrimental to US growth. A weaker currency, in this particular case, turned out to be no recipe for stronger growth. Similarly, the appreciation of the euro, triggered by a fall in the risk premium of the currency, may have been positive for growth. There are caveats to the exercise, but the results are nonetheless consistent with previous research pointing to the importance of the nature of the exchange rate shocks in estimating their impact on prices and growth.

We modify NiGEM in order to study the macroeconomic effects of imposing import tariffs in the US under different assumptions regarding the long-run price setting behaviour of exporters. Overall, the macroeconomic implications in the US resemble the impact of a cost shock or adverse supply shock as prices increase while output declines. Due to exchange rate movements and changes in the prices of traded goods, prices and output in other economies tend to move in the same direction. We demonstrate that the size and persistence of the macroeconomic impact following the introduction of new tariffs critically hinge upon the specific assumptions underlying the behaviour of export prices. If foreign exporters are concerned about their net-of-tariff prices, there will be little adjustment after the initial surge in tariff-inclusive export prices. As a result, the adverse macroeconomic impact will be large and persistent both in the US and abroad. While additional government spending financed by tariff revenues could mitigate the adverse impact on the protectionist economy in the short run, retaliation by its trading partners would worsen the outcome. Our simulations also raise doubts about the ability of protectionist measures to rein in global imbalances.

We analyse the costs of Brexit. The results show that by 2030 a hard Brexit would reduce cumulative GDP growth by 18 percentage points compared to a situation where the UK continued its EU membership. The economic damage in our FTA and soft Brexit scenarios is less severe than in our hard Brexit scenario, although it will still cost the UK economy roughly 12.5 percentage points and 10 percentage points of cumulative GDP growth by 2030, respectively. We find much larger negative effects than most existing studies that use macroeconometric modelling to assess the effects of Brexit. This is due to two reasons. First, we use an improved tariff version of the macroeconometric model NiGEM, which enables us better to assess the negative impact of cost-push inflation resulting from imposed trade barriers. Second, we estimate a new productivity model for the UK, which allows us to gauge adequately the negative UK-specific effects on productivity caused by Brexit.

The Irish economy has recovered at an impressive pace from the economic and financial crisis that lasted from 2008–12. Nonetheless, as a small open economy with some lingering vulnerabilities from the recent crisis, the economy remains heavily exposed to potential adverse shocks. In this paper, we explore the possible impact of external shocks on the Irish economy. We model the shocks in a two-stage process: first using NiGEM to estimate the impact on Ireland's key trading partners and the broader international environment and then examining the effect of these changes in the COSMO model of the Irish economy. The paper focusses on three relevant risks facing the economy: the potential for a hard Brexit, an increase in interest rates and a depreciation of the sterling euro exchange rate. Using this two-step approach allows us to demonstrate the transmission of external shocks to the Irish economy. The results help to quantify the potential impact on future growth, the labour market, public finances and the financial system of some key risks materialising.