IT5 {DLMtool} R Documentation

## Iterative Index Target MP

### Description

An index target MP where the TAC is modified according to current index levels (mean index over last 5 years) relative to a target level.

### Usage

```IT5(x, Data, reps = 100, plot = FALSE, yrsmth = 5, mc = 0.05)

IT10(x, Data, reps = 100, plot = FALSE, yrsmth = 5, mc = 0.1)
```

### Arguments

 `x` A position in the data object `Data` A data object `reps` The number of stochastic samples of the MP recommendation(s) `plot` Logical. Show the plot? `yrsmth` The number of historical years over which to average the index `mc` The maximum fractional change in the TAC among years.

### Details

The TAC is calculated as:

\textrm{TAC}_y = C_{y-1} I_δ

where C_{y-1} is the catch from the previous year and I_δ is the ratio of the mean index over the past `yrsmth` years to a reference index level. The maximum allowable change in TAC is determined by `mc`: e.g `mc=0.05` means that the maximum change in TAC from the previous catch is 5%.

The reference index level (`Data@Iref`) is assumed to be a proxy for MSY. In the MSE `Iref` is the index at MSY subject to observation error (`Obs@Irefbiascv`). Consequently the performance of these methods in MSE is strongly determined by the uncertainty the in reference index.

### Value

An object of class `Rec-class` with the `TAC` slot populated with a numeric vector of length `reps`

### Functions

• `IT5`: Maximum annual changes in TAC are 5 per cent.

• `IT10`: Maximum annual changes are 10 per cent.

### Required Data

See `Data-class` for information on the `Data` object

`IT5`: Ind, Iref, MPrec

`IT10`: Ind, Iref, MPrec

### Rendered Equations

See Online Documentation for correctly rendered equations

T. Carruthers

### Examples

```IT5(1, MSEtool::SimulatedData, plot=TRUE)
IT10(1, MSEtool::SimulatedData, plot=TRUE)
```

[Package DLMtool version 6.0.2 Index]