Here is my data.frame :: beef
> head(beef)
YEAR....PBE CBE PPO CPO PFO DINC CFO RDINC RFP
1 1925 59.7 58.6 60.5 65.8 65.8 51.4 90.9 68.5 877
2 1926 59.7 59.4 63.3 63.3 68.0 52.6 92.1 69.6 899
3 1927 63 53.7 59.9 66.8 65.5 52.1 90.9 70.2 883
4 1928 71 48.1 56.3 69.9 64.8 52.7 90.9 71.9 884
5 1929 71 49.0 55.0 68.7 65.6 55.1 91.1 75.2 895
6 1930 74.2 48.2 59.6 66.1 62.4 48.8 90.7 68.3 874
and
dput(head(beef))
structure(list(YEAR....PBE = structure(1:6, .Label = c("1925 59.7",
"1926 59.7", "1927 63", "1928 71", "1929 71", "1930 74.2",
"1931 72.1", "1932 79", "1933 73.1", "1934 70.2",
"1935 82.2", "1936 68.4", "1937 73", "1938 70.2",
"1939 67.8", "1940 63.4", "1941 56"), class = "factor"),
CBE = c(58.6, 59.4, 53.7, 48.1, 49, 48.2), PPO = c(60.5,
63.3, 59.9, 56.3, 55, 59.6), CPO = c(65.8, 63.3, 66.8, 69.9,
68.7, 66.1), PFO = c(65.8, 68, 65.5, 64.8, 65.6, 62.4), DINC = c(51.4,
52.6, 52.1, 52.7, 55.1, 48.8), CFO = c(90.9, 92.1, 90.9,
90.9, 91.1, 90.7), RDINC = c(68.5, 69.6, 70.2, 71.9, 75.2,
68.3), RFP = c(877L, 899L, 883L, 884L, 895L, 874L)), .Names = c("YEAR....PBE",
"CBE", "PPO", "CPO", "PFO", "DINC", "CFO", "RDINC", "RFP"), row.names = c(NA,
6L), class = "data.frame")
I want to create a multiple linear regression model for PBE depending on other variables. Following the guidance in this link , I think I should do something like the following:
> lm(formula = PBE ~ CBE + PBO + CPO + PFO +
+ DINC + CFO+RDINC+RFP+YEAR, data = beef)
Error in eval (expr, envir, enc): object "PBE" was not found so I decided to try the following, but everyone has some errors:
> lm(formula=PBE~YEAR,data=beef)
Error in eval(expr, envir, enclos) : object 'PBE' not found
> lm(formula=beef$PBE~beef$YEAR)
Error in model.frame.default(formula = beef$PBE ~ beef$YEAR, drop.unused.levels = TRUE) :
invalid type (NULL) for variable 'beef$PBE
Could you give me some idea of where the typo / error lies?
PS: I read the file using beef=read.table("beef.txt", header = TRUE, sep = "\t", comment.char="%"), and the file looks like this:
% http://lib.stat.cmu.edu/DASL/Datafiles/agecondat.html
%
% Datafile Name: Agricultural Economics Studies
% Datafile Subjects: Agriculture , Economics , Consumer
% Story Names: Agricultural Economics Studies
% Reference: F.B. Waugh, Graphic Analysis in Agricultural Economics,
% Agricultural Handbook No. 128, U.S. Department of Agriculture, 1957.
% Authorization: free use
% Description: Price and consumption per capita of beef and pork
% annually from 1925 to 1941 together with other variables relevant to
% an economic analysis of price and/or consumption of beef and pork
% over the period.
% Number of cases: 17
% Variable Names:
%
% PBE = Price of beef (cents/lb)
% CBE = Consumption of beef per capita (lbs)
% PPO = Price of pork (cents/lb)
% CPO = Consumption of pork per capita (lbs)
% PFO = Retail food price index (1947-1949 = 100)
% DINC = Disposable income per capita index (1947-1949 = 100)
% CFO = Food consumption per capita index (1947-1949 = 100)
% RDINC = Index of real disposable income per capita (1947-1949 = 100)
% RFP = Retail food price index adjusted by the CPI (1947-1949 = 100)
%
% The Data:
YEAR PBE CBE PPO CPO PFO DINC CFO RDINC RFP
1925 59.7 58.6 60.5 65.8 65.8 51.4 90.9 68.5 877
1926 59.7 59.4 63.3 63.3 68 52.6 92.1 69.6 899
1927 63 53.7 59.9 66.8 65.5 52.1 90.9 70.2 883
1928 71 48.1 56.3 69.9 64.8 52.7 90.9 71.9 884
1929 71 49 55 68.7 65.6 55.1 91.1 75.2 895
1930 74.2 48.2 59.6 66.1 62.4 48.8 90.7 68.3 874
1931 72.1 47.9 57 67.4 51.4 41.5 90 64 791
Here is the result View(beef)suggested by Patrick:
