## Introduction

-   how to interpreted `the effect of a single term` into the distribution of the response;
-   how to use the GAMLSS model for `prediction`.

## Interpretation

-   how the information we obtain from the fitted model can be used

```{mermaid}
%%| label: fig-fitting
%%| fig-cap: "How x-variables effecting the properties of the distribution."
%%| fig-width: 10
%%| fig-heigh: 10
%%| fig-box: 10
%%| echo: false
%%| format: gfm
flowchart TB
  A[Features.] --> B(Parameters) 
  B --> D[Properties, \n Characteristics]
  D -->  C(Distribution)
  B --> C
```

## graphical Partial effects {.smaller}

-   `ceteris paribus` (concentate in one term fixing the rest)

-   $\textbf{x}_j$ denote a **single** (or maximum two terms)

-   $\textbf{x}_{-j}$ all the **rest** so $\{\textbf{x}_j, \textbf{x}_{-j} \}$ are all terms in the model

-   $\omega(D)$ the **characteristic** of the distribution we are interested ${D}(y | \textbf{x}_j , \textbf{x}_{-j}; \boldsymbol{\theta})$ i.e. kurtosis

-   under **scenario**, $\textbf{S}[g()]$ ()

-   $${PE}_{\omega({D})}\left( \textbf{x}_{j} | \textbf{S} \left[ g(\textbf{x}_{-j})\right] \right)$$

## Scenarios {.smaller}

-   `fixing` values of $\textbf{x}_{-j}$ (mean or median for continuous, level with more number of observations for factors or other possible values of importance)

-   `average` over values of $\textbf{x}_{-j}$

    -   `Partial Dependence Plots` (PDF), $\textbf{S}\left[ \text{average}(\textbf{x}_{-j})\right]$\
    -   `Accumulated Local Effects`, (ALE), accumulated average local differences
    -   `Marginal Effects` (ME) average over local neighbourhood

## Characteristics

-   `predictors`, $\eta_{\theta_i}$

-   `parameters`, $\theta_i$

-   `moment`, i.e. mean and variance

-   `quantiles` i.e. median

-   `distribution`

```{R}
#| echo: false
#| warning: false
#| message: false
#| output: false
#| cache: false
library(gamlss2)
library(gamlss.ggplots)
library(gamlss.prepdata)
rent99 |> data_rm( c(2,9)) |>
 data_few2fac() -> da
madditive <- gamlss2(rent~s(area)+s(yearc)+location+bath+kitchen+
                cheating|s(area)+s(yearc)+location+bath+kitchen+cheating, 
              family=BCTo, data=da, trace=F)
m1 <- gamlss(rent~pb(area)+pb(yearc)+location+bath+kitchen+
                cheating,~pb(area)+pb(yearc)+location+bath+kitchen+cheating, 
              family=BCTo, data=da, trace=F)
f <- rent ~ n(~area+yearc+location+bath+kitchen, size=10)|    n(~area+yearc+location+bath+kitchen, size=3)
mneural <- gamlss2(f,family=BCTo, data=da)
```

## PE-parameter $\mu$ additive

```{R}
#| echo: true
#| layout-ncol: 2
library(gamlss.ggplots)
pe_param(madditive,"area")
pe_param(madditive,"yearc")
```

## PE-parameter $\mu$ NN

```{R}
#| echo: true
#| layout-ncol: 2
pe_param(mneural, "area" )
pe_param(mneural, "yearc" )
```

## PE; parameter $\sigma$; additive

```{R}
#| echo: true
#| layout-ncol: 2
pe_param(madditive,"area", parameter="sigma")
pe_param(madditive,"yearc", parameter="sigma")
```

## PE; parameter $\sigma$; NN

```{R}
#| echo: true
#| layout-ncol: 2
pe_param(mneural,"area", parameter="sigma")
pe_param(mneural,"yearc", parameter="sigma")
```

## all terms (additive)

```{R}
#| echo: true
pe_param_grid(madditive,c("area", "yearc",  "location", "bath", "kitchen"))
```

## 2 way interactions (additive)

```{R}
#| echo: true
#| layout-ncol: 2
 pe_param(madditive, c("area", "yearc")) 
pe_param( madditive, c("area", "yearc"), filled=TRUE) 
```

## pe_pdf

```{r}
#pe_pdf(madditive,"area")
#pe_pdf(madditive,"yearc")
```

## ALE; parameters $\mu$; Additive

```{R}
#| echo: true
#| layout-ncol: 2
gamlss.ggplots:::ale_param(madditive,"area")
gamlss.ggplots:::ale_param(madditive,"yearc")
```

## ALE; parameters $\mu$; NN

```{R}
#| echo: true
#| layout-ncol: 2
gamlss.ggplots:::ale_param(mneural,"area")
gamlss.ggplots:::ale_param(mneural,"yearc")
```

## ALE interactions

```{R}
#| echo: true
#| layout-ncol: 2
gamlss.ggplots:::ale_param(madditive,c("area", "yearc"))
gamlss.ggplots:::ale_param(mneural,c("area", "yearc"))
```

## moments (mean)

-   Not implemented yet for `gamlss2` objects

-   Note that moments not always exist for example for the `BCTo` distribution

    -   for $\tau\le2$ the variance do not exist

    -   for $\tau\le1$ the mean do not exist

## quantiles, additive

```{R}
#| echo: true
 gamlss.ggplots:::pe_quantile(madditive,c("area"))
```

## quantiles, additive (con.)

```{R}
gamlss.ggplots:::pe_quantile(madditive,c("location"))
```

## quantiles interactions

```{R}
#| echo: true
  gamlss.ggplots:::pe_quantile(madditive,c("area", "yearc"))
```

## quantiles interactions 2

```{R}
#| echo: true
 gamlss.ggplots:::pe_quantile(madditive,c("area", "location"))
```

## quantiles interactions 2

```{R}
#| echo: true
gamlss.ggplots:::pe_quantile(madditive,c( "location", "bath"))
```

## distributions, $\mu$, additive

```{R}
#| echo: true
gamlss.ggplots:::pe_pdf_grid(madditive, list("area", "yearc", "location","bath"))
```

## distributions, $\mu$, NN

```{R}
#| echo: true
gamlss.ggplots:::pe_pdf_grid(mneural, list("area", "yearc", "location","bath"))
```

## the purpose of the study {.smaller}

-   the `purpose` should be always in our mind when we try to analyse any data

-   for the Munich rent data are collected almost every 10 years

-   guidance to judges on whether a **disputed rent** is a fair or not

-   `purpose` is to identify very low or very hight rents by correcting for the explanatory variables

-   similar in detecting "outliers"

-   a possible solution: `prediction z-scores`

## prediction z-scores

Scenarios

| rent | area | yearc | location | bath | kitchen | heating |
|-----:|-----:|------:|---------:|-----:|--------:|--------:|
| 1500 |  140 |  1983 |        3 |    1 |       1 |       1 |
| 1000 |   55 |  1915 |        1 |    0 |       0 |       0 |
|  800 |   65 |  1960 |        1 |    1 |       1 |       1 |

## prediction z-scores (con.)

```{R}
#| echo: true
#| eval: true
#| warning: false
#| message: false
#| output: true
     rent <- c(1500, 1000,800)
     area <- c(140, 55, 65)
    yearc <- c(1983, 1915, 1960)
 location <- factor(c(3,1,1))
     bath <- factor(c(1,0,1))
  kitchen <- factor(c(1,0,1))
 cheating <- factor(c(1,0,1))
 ndat <- data.frame(rent, area, yearc, location, bath, kitchen, cheating)
 cat("prediction z-scores", "\n")
 pp <-predict(madditive, newdata=ndat, type="parameter")
  qNO(madditive$family$cdf(q=ndat$rent, par=pp))
```

## summary

`GAMLSS` can tackle problems where the interest of the investigation lies **not only** in the `center` but `other parts of the distribution.`

Personal view for the future of `GAMLSS` development;

-   theoretical contributions

-   software and

-   knowledge exchange

## Summary (continue)

-   `theoretical contributions`
    -   interpretable tools
    -   model average for prediction
-   `software`
    -   `gamlss2`
-   `books and knowledge exchange`
    -   there is need for applied and elementary books
    -   more application public health and environment

## the team {.smaller}

| working party | current | past |
|:---------------------|:---------------------|:---------------------------|
| `Gillian Heller` | `Konstantinos Pateras` | Popi Akantziliotou, |
| `Fernanda De Bastiani` | Paul Eilers , `Kevin Burke` | Vlasios Voudouris, Nadja Klein |
| `Thomas Kneib` | `Nikos Kametas` | Marco Enea, Nicoleta Mortan |
| `Achim Zeileis` | Tim Cole | Daniil Kiose, Florian Ziel |
| `Andreas Mayr` | `Artur Fredrich` | Dea-Jin Lee, Peru Muniain |
| `Nicolaus Umlauf` | `Luiz Nakamura` | María Xosé Rodríguez-Álvarez |
| `Reto Stauffer` | `Elisa Van Eynde` | Majid Djennad |
| `Robert Rigby` | `Julian Merder` | Nikos Georgikopoulos |
| `Mikis Stasinopoulos` | Abu Hossain | Raydonal Ospina, Fiona McElduff |

## end

[back to the index](https://mstasinopoulos.github.io/Brazil2025/)

::: {layout-ncol="3," layout-nrow="1"}
![](book-1.png){width="300"} ![](BOOK-2.png){width="323"} ![](book3.png){width="333"} The Books
:::