NEW YORK—A study published Thursday by the McKinsey Global Institute confirmed that American citizens lead the world in the ability to justify needless purchases, a finding that extended across all consumer categories, from electronics, to food items, to motor vehicles. “When it comes to rationalizing a third flatscreen television, defending the bulk purchase of sale items, inventing reasons to upgrade a cable package, and categorizing any purchase as an ‘investment,’ we discovered that consumers in the U.S. are more than five times as proficient as their counterparts in other countries,” said researcher Peter Cahill, citing the roughly $100 billion per year that Americans justify spending on cell phones that are less than a year newer than their existing model, shoes with pockets for each toe, brand-name allergy medicine, in-home soda machines, apps, coconut water, collector’s edition DVDs, and thousands of other goods and services. “What’s perhaps more impressive is that the unnecessary spending gap between the U.S. and the next closest nation more than doubles when we factor in completely superfluous big-ticket purchases, such as tuition at exclusive colleges or 3,400-square-foot homes.” The study also found that U.S. consumers were equally dominant when it came to helping friends and family members justify the purchase of unnecessary products.