def extract_data_values(data, value_key):
    """Extract value from a pandas.DataFrame

    Parmeters
    ---------
    data : dict
        The raw data.
    value_key : string
        A column in data which contains the values we are to extract.

    Returns
    -------
    values : dict
        A dict where the keys are the id's found in data_key and
        the values are the correconding values from data_value.

    """
    values = {}
    for key in data:
        values[key] = data[key][value_key]
    return values