# FMPMonotonicityCheck: Utility function for checking FMP monotonicity In fungible: Psychometric Functions from the Waller Lab

 FMPMonotonicityCheck R Documentation

## Utility function for checking FMP monotonicity

### Description

Utility function for checking whether candidate FMP coefficients yield a monotonically increasing polynomial.

### Usage

FMPMonotonicityCheck(b, lower = -20, upper = 20, PLOT = FALSE)


### Arguments

 b A vector of 8 polynomial coefficients (b) for m(\theta)=b_0 + b_1 \theta + b_2 \theta^2 + b_3 \theta^3 + b_4 \theta^4 + b_5 \theta^5 + b_6 \theta^6 + b_7 \theta^7. lower, upper \theta bounds for monotonicity check. PLOT Logical (default = FALSE). If PLOT = TRUE the function will plot the original polynomial function for \theta between lower and upper.

### Value

 increasing Logical indicating whether function is monotonically increasing. minDeriv Minimum value of the derivative for the polynomial. minTheta Value of \theta at derivative minimum.

Niels Waller

### Examples



## A set of candidate coefficients for an FMP model.
## These coefficients fail the test and thus
## should not be used with genFMPdata to generate
## item response data that are consistent with an
## FMP model.
b <- c(1.21, 1.87, -1.02, 0.18, 0.18, 0, 0, 0)
FMPMonotonicityCheck(b)



fungible documentation built on March 31, 2023, 5:47 p.m.