昨天我看宏经书时，遇到几个问题，还请大家帮忙解答一下哈。
1 seasonal adjustment  ----"……in addition,when the government reports quaterly GDP,it presents the data after they have modified by a statistical procedure called 'seasonal adjustment'.The unadjusted data show clearly that the economy produces more goods and services during some times of year than during others(As you might guess,December's holiday shopping season is a high point )when monitoring the condition of the economy,economists and policymakers often want to look beyond these regular seasonal changes.Therefore ,government statisticians adjust the quarterly data to take out the seasonal cycle.The GDP data reported in the news are always seasonally adjusted……" 请问下经过调整的数据和未经调整的数据有什么区别啊？对数据进行调整的原因是什么啊？
  2 我在看书时，经常看到"negative tax"这个东东，比如“……but what happens when the government pays a Social Security benefit to one of the elderly?Such government spending is called a transfer payment because it is not made in exchange for a currently produced good or service.Transfer payments alter househeld income,but they do not reflect the economy's production.(From a macroeconomic standpoint,transfer payment are like negative tax) 请问这个negative tax是一种什么税啊？翻译的话应该怎么翻译比较好哈？还有上文中那个Social Security benefit具体是一种怎样的社会转移支付啊？弱弱的问题，大家表要打我哈，谢谢大家了