def evaluate_probabilities(data):
    """Calculate accuracy of logistic regression model
    Args:
        data (pandas.DataFrame): dataframe with nudge success and probability
    Returns:
        int: accuracy in percentage
    """
    check = round(data['probability']) == data['outcome']
    correct = sum(check)
    total = check.shape[0]
    accuracy = int(round(correct*100/total, 0))
    print("Correct prediction of nudge success for {}% ({} out of {})". format(
        accuracy, correct, total))

    return accuracy