A: What do you think is the reason Mike failed?

B: Mike’s mistake was to take a half measure when he should have taken a full one.

Note: This idiom means “a partial, halfhearted, or weak line of action.” Literally, a measure refers to a standard unit expressing the size, amount, or degree of something. A measure of whisky is two fingers tall in a glass. A measure is also a step or a procedure one takes in order to achieve something. If someone takes a half measure in doing something, they’re half-hearted in the endeavor. Half measures are inadequate measures just as a half measure of whisky is inadequate.