grade.discreteprobability {grade}R Documentation

Grade Discrete Probability Sets

Description

Checks a students probability distribution, makes sure that (1) It sums to 1 (2) All elements are >= 0

Optionally, it compares the students to a correct one. Order is optionally enforced.

Usage

grade.discreteprobability(correctans, studentans, tolerance=.01,
                          useeval=TRUE, usena=FALSE, useinf=FALSE,
                          quiet=TRUE, ordered=FALSE, checkcorrect=TRUE)

Arguments

correctans a vector of type numeric or a string
studentans a vector of type numeric or a string
tolerance a string or numeric representing the accepted component wise tolerance
useeval TRUE or FALSE indicates whether or not to use 'eval' on strings
usena TRUE or FALSE indicating whether or not NA is an accepted value
useinf TRUE or FALSE indicating whether or not Inf and -Inf are accepted values
quiet TRUE or FALSE. If TRUE there are more warning messages when checks fail. Can be helpful for debugging.
ordered TRUE or FALSE. If TRUE studentans order must match correctans order to be considered correct. If FALSE, order does not matter (so both are sorted and then checked)
checkcorrect TRUE or FALSE. if TRUE studentans needs to match correctans. If FALSE studentans only needs to qualify as a discrete probability distribution.

Details

If checkcorrect=FALSE, grade.discreteprobability does not do any checks on correctans. In this case to be correct, studentans needs to satisfy discrete probability constraints – all elements >= 0 and sums to 1.

If checkcorrect=TRUE discrete probability constraints are enforced on correctans. studentans needs to match correctans in this case. Order is only enforced if ordered=TRUE.

grade.discreteprobability does not use NA. If usena=TRUE grade.discreteprobability sets it to FALSE and issues a warning message.

Value

TRUE or FALSE indicating match success or failure respectively. FALSE is also returned if studentans does not look like a set.

Note

The grade main page contains a discussion of the common parameters correctans, studentans, useeval, usena, useinf, quiet.

See Also

grade grade.set

Examples

# TRUE
grade.discreteprobability(c(1/2,1/2), "[.5, .5]")
# TRUE
grade.discreteprobability(NULL, "[0, .33, .17, .5]", checkcorrect=FALSE) 

# FALSE
grade.discreteprobability(NULL, "[-1, 0, 0, 1, 1]", checkcorrect=FALSE)

# TRUE
grade.discreteprobability(c(0, 1/2, 1/4, 1/4), "[0, 1/2, 1/4, 1/4]")
# FALSE
grade.discreteprobability(c(0, 1/2, 1/4, 1/4), "[0, .25, .25, .5]",
                          ordered=TRUE)

# TRUE
grade.discreteprobability(c(0, 1/2, 1/4, 1/4), "[0, .5, .25, .25]",
                          ordered=TRUE)

[Package grade version 0.2 Index]