# Introduction

The parameters of a study on Mabyduck are controlled by two types of objects: experiments and jobs.
An **experiment** decides the type of study, the details of the user interface, and the data to be evaluated.
For example, a [MUSHRA](/experiments/audio/mushra/) experiment evaluating a set of
compressed audio files. Each experiment can have multiple **jobs**. These define who
the raters are, and how much data each rater will evaluate. This allows you to run the same
experiment with different groups of raters, and see how they compare.

The most important concepts of the Mabyduck platform are:

```mermaid
  graph RL
   Job --> Experiment
   Session --> Job
   Slate --> Session
   Stimulus -- "Rating" --> Slate
```

When a rater participates in a study, this creates a **session** associated with the job. Depending
on the configuration of a job, a rater might participate multiple times in a study, creating
multiple sessions.

Each session consists of multiple *slates* that represent a group of *stimuli* evalauted together. In the
simplest case, a slate is associated with a single stimulus that was rated on an absolute category
rating scale (e.g., on a scale from 1 to 5).
For a MUSHRA experiment, a slate corresponds to the set of audio files that were rated together.