[R-SIG-Finance] Calculating Proportions & Appending New Column?

[Jason Eyerly]

Hello Folks,
	I’m doing a study for a coursera Data Science class, and I am trying to determine if American’s financial satisfaction has any correlation to the percentage return of the S&P500 in the year prior. I have to calculate the proportion of "Satisfied" and "More Or Less" compared to the total number of observations for year "X", starting at 1989. After computing that for each year, I need to place them in a column at the end of the dataset similar to what we see with "PercentChange”. However, the years only go from 1989 - 2012. Calculating it for each observation seems tedious and inefficient. The end result is a chart where the X-Axis is each different percent change, and the Y-Axis is the proportion that are satisfied. What's the most efficient way to do this? Sorry for posting all of my code, but I don’t know what’s important and what isn’t. I realize I probably didn’t code everything in the most efficient way possible.

require(Quandl)
require(lubridate)
require(zoo)
require(xts)

myGSS <- load(url("http://bit.ly/dasi_gss_data"))

year <- gss$year
finSat <- gss$satfin

relativeTable <- data.frame(year, finSat)
relativeTable <- subset(relativeTable, year > "1988" & !is.na(finSat))


spReturns <- Quandl("SANDP/ANNRETS", trim_start="1970-01-11", 
                    trim_end="2012-12-31", authcode="nwy3a_Gmd7TSS9fVirxT", 
                    collapse="annual")

percentChange <- spReturns$"Total Return Change"

spReturns$"Year Ending" <- format((spReturns$"Year Ending"), "%Y")
spReturns$"Year Ending" <- as.numeric(spReturns$"Year Ending")
spReturns$"Year Ending" <- spReturns[,1] + 1 #the following year

combined <- merge(relativeTable, spReturns, by.x = "year", by.y = "Year Ending")
names(combined)[6] <- "percentChange"

finalResults <- data.frame(combined$year, combined$finSat, combined$percentChange)
names(finalResults)[1] <- "Year"
names(finalResults)[2] <- "FinancialSatisfaction"
names(finalResults)[3] <- "PercentChange"

finalResults$PercentChange <- finalResults$PercentChange * 100

Regards,
    Jason E.
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