The paper explores why Central Banks change interest rates infrequently, how interest rates behave weekly, and what factors drive rate changes. Central Banks smooth interest rate adjustments due to fixed costs, using a discrete policy rule. By analyzing Swedish data, the study shows that unemployment, inflation, retail sales, industrial production, money growth, and U.S. and German interest and exchange rates influence Swedish repo rate changes. The model accurately predicts whether the target rate will be raised, lowered, or kept constant, with an 88% success rate compared to 78% for a basic estimator.