必须要用实证吧，个人认为应该做个线性回归分析，搜集数据用SPSS应该就可以做的

That's very interesting.

You may get the following data,
Debt/Asset
Debt/Equity
and
ROA, ROE or EVA;
Operation cycle; inventory turnover and A/R turnover.

As my neighbor suggested, build a model to verify your assumption.
There should be something interested unless the data is not reliable.

Other matter
The industrial difference and operation scale may influence your findings.
Stratify your data may reduce those impact.
I hope it helps.
Good luck my friend.