# Getting Started with ParCC

## What is ParCC?

ParCC (Parameter Converter & Calculator) is a decision support tool for Health Technology Assessment (HTA). It bridges the gap between reported clinical statistics and the specific input parameters required for health economic models such as Markov cohort models, decision trees, and partitioned survival models.

## Installation

Install ParCC from GitHub:

    # install.packages("remotes")
    remotes::install_github("drpakhare/ParCC")

## Launching the Application

    library(ParCC)
    run_app()

This opens a browser-based Shiny application with all calculation tools.

## The Lab Notebook Workflow

Reproducibility is critical in HTA. Every parameter in your model must be traceable to its source and methodology. ParCC acts as your digital logbook.

The 4-Step Workflow:

1. Label It: Before calculating, type a specific name in the ‘Label’ box (e.g., “PFS Control Arm” or “Cost of Surgery - AIIMS 2023”).

2. Calculate & Log: Click the blue action button. This calculates the result AND saves it to your session log with a timestamp.

3. Review: Navigate to the Report tab to see a table of all logged parameters.

4. Export: Download the HTML Report. This document serves as a Technical Appendix for your manuscript or HTA dossier, complete with formulas and references.

## Application Overview

ParCC provides 12 calculation modules organized into four categories:

### Parameter Estimation

- Converters – Rate/Odds to Probability, Time Rescaling
- HR Converter – Apply Hazard Ratios from trials to convert control probabilities to intervention probabilities
- Bulk Conversion – Upload a CSV and convert an entire column
- Survival Analysis – Fit Exponential or Weibull curves from summary data
- Background Mortality – SMR adjustment, Gompertz fitting, DEALE, interpolation

### Uncertainty Analysis

- PSA – Fit Beta, Gamma, and LogNormal distributions for Probabilistic Sensitivity Analysis

### Financial Adjustments

- Financial – Inflation adjustment and discounting calculators

### Decision Outputs

- Diagnostics – Bayesian PPV/NPV
- ICER & NMB – Cost-effectiveness metrics
- Value-Based Pricing – Headroom analysis

## Next Steps

Explore the other vignettes for detailed tutorials:

- `vignette("core-conversions")` – Rates, Odds, and Time Rescaling
- `vignette("hr-probability-converter")` – Applying Hazard Ratios
- `vignette("survival-extrapolation")` – Fitting survival curves
- `vignette("background-mortality")` – Mortality adjustments
- `vignette("psa-distributions")` – Parameterizing PSA
- `vignette("economic-evaluation")` – ICER, NMB, and VBP
- `vignette("batch-workflow")` – Bulk CSV processing

## References

- Briggs A, Claxton K, Sculpher M. Decision Modelling for Health Economic Evaluation. Oxford University Press; 2006.
- Drummond MF, et al. Methods for the Economic Evaluation of Health Care Programmes. 4th ed. Oxford University Press; 2015.