Getting Started

Installation

Using pip, you can install adopy from PyPI.

pip install adopy

Instead, you can install the developmental version in the GitHub repository.

git clone https://github.com/adopy/adopy.git
cd adopy
git checkout develop
pip install .

Quick-start guide

Here, we present how to use ADOpy to compute optimal designs for an experiment. Assuming an arbitrary task and a model, this section shows how users can apply the Adaptive Design Optimization procedure into their own tasks and models from the start.

A simple diagram for the Adaptive Design Optimization.

Step 1. Define a task using adopy.Task

Assume that a user want to use ADOpy for an arbitrary task with two design variables (x1 and x2) where participants can make a binary choice on each trial. Then, the task can be defined with adopy.Task as described below:

from adopy import Task

task = Task(name='My New Experiment',  # Name of the task (optional)
            designs = ['x1', 'x2'],    # Labels of design variables
            responses = [0, 1])        # Possible responses

Step 2. Define a model using adopy.Model

To predict partipants’ choices, here we assume a logistic regression model that calculates the probability to make a positive response using three model parameters (b0, b1, and b2):

\[p = \frac{1}{1 + \exp\left[ - (b_0 + b_1 x_1 + b_2 x_2) \right]}\]

How to compute the probabilty \(p\) should be defined as a function:

import numpy as np

def calculate_prob(x1, x2, b0, b1, b2):
    """A function to compute the probability of a positive response."""
    logit = b0 + x1 * b1 + x1 * b2
    p_obs = 1. / (1 + np.exp(-logit))
    return p_obs

Using the information and the function, the model can be defined with adopy.Model:

from adopy import Model

model = Model(name='My Logistic Model',   # Name of the model (optional)
            params=['b0', 'b1', 'b2'],  # Labels of model parameters
            func=calculate_prob)        # A probability function

Step 3. Define grids for design variables and model parameters

Since ADOpy uses grid search to search the design space and parameter space, you must define a grid for design variables and model parameters. The grid can be defined using the labels (of design variables or model parameters) as its key and an array of the corresponding grid points as its value.

import numpy as np

grid_designs = {
    'x1': np.linspace(0, 50, 100),    # 100 grid points within [0, 50]
    'x2': np.linspace(-20, 30, 100),  # 100 grid points within [-20, 30]
}

grid_param = {
    'b0': np.linspace(-5, 5, 100),  # 100 grid points within [-5, 5]
    'b1': np.linspace(-5, 5, 100),  # 100 grid points within [-5, 5]
    'b2': np.linspace(-5, 5, 100),  # 100 grid points within [-5, 5]
}

Step 4. Initialize an engine using adopy.Engine

Using the objects created so far, an engine should be initialized using adopy.Engine. It contains built-in functions to compute an optimal design using ADO.

from adopy import Engine

engine = Engine(model=model,              # a Model object
                task=task,                # a Task object
                grid_design=grid_design,  # a grid for design variables
                grid_param=grid_param)    # a grid for model parameters

Step 5. Compute a design using the engine

# Compute an optimal design based on the ADO
design = engine.get_design()
design = engine.get_design('optimal')

# Compute a randomly chosen design, as is typically done in non-ADO experiments
design = engine.get_design('random')

Step 6. Collect an observation in your experiment

# Get a response from a participant using your own code
response = ...

Step 7. Update the engine with the observation

# Update the engine with the design and the corresponding response
engine.update(design, response)

Step 8. Repeat Step 5 through Step 7 until the experiment is over

NUM_TRIAL = 100  # number of trials

for trial in range(NUM_TRIAL):
    # Compute an optimal design for the current trial
    design = engine.get_design('optimal')

    # Get a response using the optimal design
    response = ...  # Using users' own codes

    # Update the engine
    engine.update(design, response)

More examples

There are more examples on how to use ADOpy for other experimental tasks.