def get_theta_params(pkey, kind='dpm'):
    """ set and return loc, scale of parameter pkey
    ::Arguments::
        pkey (str): parameter name to get loc and scale for sampling
    ::Returns::
        theta[pkey] (tuple): (loc, scale)
    """
    theta = {'a': (0.35, 0.15), 'si': (0.001, 0.1), 'sso': (0.05, 0.035),
        'ssv': (-0.5, 0.3), 'tr': (0.25, 0.075), 'v': (0.8, 0.3), 'xb': (
        1.0, 0.35), 'z': (0.3, 0.2)}
    thetaRL = {'AX': (0.0005, 0.3), 'BX': (0.001, 0.2), 'PX': (0.0001, 
        0.005), 'vd': (0.5, 0.5), 'vi': (0.3, 0.4)}
    if 'irace' in kind:
        mu, sigma = theta['ssv']
        theta['ssv'] = abs(mu), sigma
    theta.update(thetaRL)
    return theta[pkey]
