def decrease_parameter_closer_to_value(old_value, target_value, coverage):
    """
    Simple but commonly used calculation for interventions. Acts to decrement from the original or baseline value
    closer to the target or intervention value according to the coverage of the intervention being implemented.

    Args:
        old_value: Baseline or original value to be decremented
        target_value: Target value or value at full intervention coverage
        coverage: Intervention coverage or proportion of the intervention value to apply
    """

    return old_value - (old_value - target_value) * coverage if old_value > target_value else old_value