It's no secret that employee feedback surveys are important. They provide insights into what's going on with your workforce. But as with any form of data, if you're not asking the right questions, you won't get worthwhile answers.

"Like a relationship, employees and employers continue to invest in each other over time," said Becky Cantieri, the senior vice president of the online survey company SurveyMonkey. "You can't just ask how your employees feel once a year."

She went on to say that there needs to be an ongoing dialogue. This means turning away from pre-made employee surveys and focusing on questions that better fit your company.

Here are four types of nuanced employee feedback you need to consider:

1. Net promoter score.

The net promoter score asks employees if they'd recommend the workplace to someone they know. A low score is one of the first signs that something is wrong. At the performance management company Reflektive, they gather net promoter data every month.

"We find this frequency necessary for today's pace of and approach to digital business," director of employee success, Rachel Ernst, said. "When we notice an increase or decrease in our eNPS score, we learn quickly about the causes and make adjustments as needed."

The key is to follow up by asking for anonymous comments and suggestions. This allows employees to express what they're loving or what is bothering them without fear of punishment. Then, when people see positive changes, they feel valued.

2. The Goldilocks question.

Employees like challenges. But they don't want to be worked to the bone. This is why it's important to have an understanding of their workload and stress levels. Crystal Huang, CEO of the talent management platform ProSky, likes to ask if an individual's workload "too much," too little," or "just right."

If an employee answers with the latter two options, Huang knows they're ready for more responsibilities or training.

"When they respond 'too much,' that's when we can sit down with them and go through what they are working on and how they are feeling more in-depth," she said.

Use this type of Goldilocks question in other scenarios to gauge employees' feelings. Ask them if they think they're getting enough one-on-one time with their managers. Find out if they feel like they're getting enough autonomy. See how they feel about the clarity of communication in the company. Answers to these types of questions help you see how to improve.

3. Unguided responses.

When a company relies on multiple-choice questions, it restricts employees' honesty. Instead of sharing their voice and opinions, they are forced to choose between options leaders put before them.

At HCM software company Ultimate Software, leaders prefer to ask open-ended questions. The in-depth answers the organization received revealed a problem with their paid time off policy.

"Through our surveys, we had increasingly heard from employees wishing for more time off throughout the year," chief people officer, Vivian Maza, said. "At the same time, we had managers coming to us saying that some of their direct reports weren't taking the time off when they probably should."

To fix the issue, the company instituted unlimited paid time off. This enabled employees to stay home when they were sick rather than worrying about saving vacation days.

The trick to asking effective open-ended questions is balancing openness and specificity. Asking "what do you like about work?" isn't focused enough to provide quality information. Yet, "what are your thoughts about putting cookies in the vending machine?" is too specific.

It's best to ask about general topics where you suspect there's a problem. This will keep employees' responses insightful and relevant.

4. The details.

When asked to provide their opinions or ideas, many employees think they need to give big suggestions. They want to impress. But often a small idea ends up making a big difference.

For example, the integrated marketing company rbb Communications has a prize wheel it uses to recognize its employees. To ensure everyone was benefiting from the options, CEO Christine Barney asked for feedback about the prizes.

"Our employees wanted more experiences so the prize wheel went from a free car wash to 'Box it up: choose a book of the month, Dollar Shave Club or Birchbox' experience," she said. The change made the employee experience better and gave Barney a better understanding of her employees.

To get employee feedback about smaller details, be proactive about asking for their input in a regular, informal setting. For example, after a brainstorming session, talk with someone who was quiet at the meeting. Find out their view of the situation. Their response could show you that your meeting structure doesn't encourage everyone to speak up.