epitools (version 0.5-2)

expected: Expected values in a table

Description

Assuming independence, calculates expected values in a matrix or table.

Usage

expected(x)

Arguments

x

is a matrix or table

Value

• expected values

Details

Assuming independence, calculates expected values in a matrix or table.

References

Steve Selvin (2001), Epidemiologic Analysis: A Case-Oriented Approach, Oxford University Press

See Also

See also margin.table

Examples

##From Selvin, 2001, p.2
##year = year of birth
##one+ = one or more congenital defects
##one = one congenital defect
dat <- scan()
  369  460
  434  434
  506  487
  521  518
  526  488
  605  481
  649  477
  733  395
  688  348

##observed
oi <- matrix(dat, nrow =2)
colnames(oi) <- 1983:1991
rownames(oi) <- c("one+", "one")

##expected
ei <- expected(oi)

##Pearson chi-square test 
chi2.T <- sum((oi - ei)^2/ei)
pchisq(q = chi2.T, df = 8, lower.tail = FALSE)