(Proportion of Total Assets invested in Stocks) In the last decade stockbrokers have drastically changed the way they do business. Internet trading has become quite common and online trades can cost as little $7. It is now easier and cheaper to invest in the stock market than ever before. What are the effects of these change? To help answer this question, a financial analyst randomly sampled 366 American households and asked each to report the age of the head of the household and the proportion of their financial assets that are invested in the stock market. The age categories are: Young(<35), Early Middle Age (35-49), Late Middle Age (50-65) and Senior (over 65). The analyst was particularly interested in determining whether the ownership of stock varied by age. Some of data are as follow:

Professor: Hyungju Cha

	Young	Early Middle Age	Late Middle Age	Senior
Mean	44.40	52.57	51.14	51.84
V ariance	386.55	469.44	471.82	447.79
# of Obs.	84	131	93	58
Grand Mean=50.18