European options vs. American options
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For European options, the options could be exercised on maturity dates, 

   while American options could be exercised any time before and on maturity dates. 

      C(European)  <=  C(American)

      P(European)  <=   P(American)

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Links 
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Yahoo!Finance :  http://finance.yahoo.com/
Google finance:  https://www.google.com/finance
Market Watch  :  http://www.marketwatch.com
SEC filings   :  https://www.sec.gov/edgar.shtml
Compustat     :  https://en.wikipedia.org/wiki/Compustat

Financial ratios
     http://www.accountingverse.com/managerial-accounting/fs-analysis/financial-ratios.html
6 Basic Financial Ratios And What They Reveal (YouTube,2m3s)
     http://www.investopedia.com/financial-edge/0910/6-basic-financial-ratios-and-what-they-tell-you.aspx
Cash Flow statements
     http://harbert.auburn.edu/~colqull/FINC3610/Chap9notes.pdf
Understanding the COMPUSTAT (North America) Database 
     http://web.utk.edu/~prdaves/Computerhelp/COMPUSTAT/Compustat_manuals/user_02.pdf
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ROA and ROE
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infile<-"http://datayyy.com/data_R/ibmBS.RData"
a<-load(url(infile))
print(a)
BS<-.x
infile<-"http://datayyy.com/data_R/ibmIS.RData"
a<-load(url(infile))
print(a)
IS<-.x

namesIS<- toupper(rownames(IS))
namesBS<-toupper(rownames(BS))

p<-"net income"
netIncome<-IS[grep(toupper(p),namesIS),]
print(netIncome)

p<-"Common Stock equity"
equity<-BS[grep(toupper(p),namesBS),]

print(equity)
netIncome2<-as.numeric(netIncome[1,])

equity2<-as.numeric(equity)
ROE<-netIncome2/equity2
print(" ---- ROE ---------------")
print(ROE)
#
TA<- toupper("Total Assets")
totalAssets<-BS[grep(TA,namesBS),]
totalAssets
print(" ---- ROA ---------------")
ROA<-netIncome[,1]/totalAssets
print(ROA)
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infile<-"http://datayyy.com/data_R/ibmBS.RData"
a<-load(url(infile))
print(a)
BS<-.x
infile<-"http://datayyy.com/data_R/ibmIS.RData"
a<-load(url(infile))
print(a)
IS<-.x
head(BS,2)
head(IS,2)

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