Description Usage Arguments Value References See Also Examples

The measurement level of a `"item"`

object, which is one of "nominal", "ordinal", "interval", "ratio",
determines what happens to it, if it or the `data.set`

containing it is coerced into a `data.frame`

.
If the level of measurement level is "nominal", the it will be
converted into an (unordered) factor, if the level of measurement is "ordinal",
the item will be converted into an ordered vector. If the measurement
is "interval" or "ratio", the item will be converted into a numerical vector.

1 2 3 4 5 6 7 8 9 10 11 12 13 | ```
## S4 method for signature 'item'
measurement(x)
## S4 replacement method for signature 'item'
measurement(x) <- value
## S4 method for signature 'data.set'
measurement(x)
## S4 replacement method for signature 'data.set'
measurement(x) <- value
is.nominal(x)
is.ordinal(x)
is.interval(x)
is.ratio(x)
set_measurement(x,...)
``` |

`x` |
an object, usually of class |

`value` |
for the |

`...` |
vectors of variable names, either symbols or character strings, tagged with the intended measurement level. |

The `item`

method of `measurement(x)`

returns a character
string, the `data.set`

method returns a named character vector,
where the name of each element is a variable name and each

`is.nominal`

, `is.ordinal`

, `is.interval`

, `is.ratio`

return a logical value.

Stevens, Stanley S. 1946. "On the theory of scales of measurement." *Science* 103: 677-680.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | ```
vote <- sample(c(1,2,3,8,9),size=30,replace=TRUE)
labels(vote) <- c(Conservatives = 1,
Labour = 2,
"Liberal Democrats" = 3,
"Don't know" = 8,
"Answer refused" = 9
)
missing.values(vote) <- c(8,9)
as.data.frame(vote)[[1]]
measurement(vote) <- "interval"
as.data.frame(vote)[[1]]
group <- sample(c(1,2),size=30,replace=TRUE)
labels(group) <- c(A=1,B=2)
DataS <- data.set(group,vote)
measurement(DataS)
measurement(DataS) <- list(interval=c("group","vote"))
head(as.data.frame(DataS))
DataS <- set_measurement(DataS,
nominal=c(group,vote))
head(as.data.frame(DataS))
``` |

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