WASHINGTON (AP) " A trade group says the nation's service sector shrank for the fourth straight month in January, but at a slower pace than the previous month.The Institute for Supply Management, a trade association of purchasing executives, says its service sector index rose to 42.9 last month, from December's downwardly revised reading of 40.1.That January reading was above analysts' expectations of 39, according to a survey by Thomson Reuters. Any reading above 50 signals growth, while a reading below 50 indicates contraction.The ISM survey says new orders and production rose last month, while an employment index fell. …