How can i improve these lines of code?

I've a function which i think can be improved, the code is pretty naive.

public function isValid($data)
{
    $valid = true;

    $valid = parent::isValid($data) && $valid;
    $this->_errorsExist = !$valid;

    return $valid;
}

The parent::isValid($data) will also return boolean.

I corrected it by removing the $valid in && condition.

public function isValid($data)
{
    $valid = true;

    $valid = parent::isValid($data);
    $this->_errorsExist = !$valid;

    return $valid;
}

But i think this still can be improved. Any suggestions would greatly be appreciated.