Suppose that during 2019 the market for implementing sales management software increased by 5%, and that Haller experiences a 1 % decline in prices. Assume that any further decreases in selling prices and increases in market share are strategic choices by Haller's management to implement Haller's cost leadership strategy.

Required
Calculate how much of the change in operating income between 2018 and 2019 is due to industry market-size factors, cost leadership, and product differentiation. How successful has Haller been in implementing its strategy?