---
title: "Parameter estimates and fit statistics of LCSMs"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Parameter estimates and fit statistics of LCSMs}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```

```{r setup}
library(lcsm)
library(lavaan)
```

The main underlying functions to extract parameters and fit statistics come from the `broom` package: `broom::tidy()` and `broom::glance()`. 
The functions `extract_param()` and `extract_fit()` offer some tools that I find helpful when running LCSMs in R, for example:

-  `extract_param()`: only one row per estimated parameter,
- `extract_fit()`: fit statistics for multiple `lavaan` objects can be extracted.

## Create univariate models

```{r}
# First fit some latent change score models

# No change model
uni_lcsm_01 <- fit_uni_lcsm(data = data_uni_lcsm, 
                            var = c("x1", "x2", "x3", "x4", "x5"),
                            model = list(alpha_constant = FALSE, 
                                         beta = FALSE, 
                                         phi = FALSE))
# Constant change only model
uni_lcsm_02 <- fit_uni_lcsm(data = data_uni_lcsm, 
                            var = c("x1", "x2", "x3", "x4", "x5"),
                            model = list(alpha_constant = TRUE, 
                                         beta = FALSE, 
                                         phi = FALSE))

# Constant change and proportional change (Dual change model)
uni_lcsm_03 <- fit_uni_lcsm(data = data_uni_lcsm, 
                            var = c("x1", "x2", "x3", "x4", "x5"),
                            model = list(alpha_constant = TRUE, 
                                         beta = TRUE, 
                                         phi = FALSE))

```

## Extract fit statistics

This function takes the `lavaan` objects as input and returns some fit statistics.
More fit statistics can be returned using the argument `details = TRUE`.

```{r}
# Extract fit statistics
fit_uni_lcsm <- extract_fit(uni_lcsm_01, uni_lcsm_02, uni_lcsm_03)

# Print table of parameter estimates
knitr::kable(fit_uni_lcsm, 
             digits = 3, 
             caption = "Parameter estimates for bivariate LCSM")

```

## Extract parameters

```{r}
# Now extract parameter estimates
param_uni_lcsm_02 <- extract_param(uni_lcsm_03, printp = TRUE)

# Print table of parameter estimates
knitr::kable(param_uni_lcsm_02, 
             digits = 3, 
             caption = "Parameter estimates for bivariate LCSM")

```


# TODOs

- For now see example in README file on Github or shinyApp "shinychange"
- step by step example here building all the way up to a univariate lcsm
- select data
- run univariate models
- add parameters and compare results using anova and model parameters
- use grimm 2017 data?
.
