Research is a task that requires time, patience, skill and expertise in the particular subject area. When you start a research you think about the time and other resources available to you. These resources will be required as you will carry out the research. If you have lots of money and time you can manage to work on a broad topic otherwise you narrow down your research topic and focus on it. In this way you can easily justify your research. In Ph. D thesis and dissertation you are given a very specific time and you have to complete your research at this time. Your time is money in the case of research and you have to develop a topic that can make better use of this money.
Why you narrow down your research topic?
Researchers often think that their topic has been narrowed down enough but in reality it is not. You need to narrow down your topic for following reasons.
1. Broad topics cannot be justified in a limited time and you cannot develop a focal point. Your thoughts and actions wander from one point to another.
2. Broad topics require more time, money and energy to accomplish the research.
3. When the topic is broad there are many dimensions and you cannot control these dimensions. Due to many dimensions the chances of bias increase.
4. The evaluation of data also becomes difficult and you cannot make appropriate conclusions.
5. In depth knowledge cannot be generated because you have to focus on many subject areas.
6. Often researchers get bored of their topic as it gets lengthy.
How to narrow down your research topic?
To narrow down your research topic you can use any of the various methods but the simplest method can be as follows:
1. To narrow down your research topic first write down your research subject area and then the research topic that you have decided.
2. Your next task should be to brainstorm the different aspects or dimensions of your research topic. From these topics select one dimension that best suits your research.
3. Now you are in a position to rephrase your research topic. Read out your new research topic again and again to look for any chances of narrowing down again. Narrow it until you get satisfied with the width and depth of your research topic.
4. Now decide whether you want to make it a comparative study, a correlational study, a descriptive or historical study. You need to rephrase your topic again.
5. In the end check your topic for any loopholes, if there are any fix them now.
6. One thing you should keep in mind research is a task of responsibility and from the start do not take anything for granted and be very clear about your research topic.

Research Topic
Obese teenagers are most likely to have prediabetes, a disorder where blood sugar levels suggest a high risk for advancement of diabetic issues.
No, obesity is the worst thing when we narrow down our research on what causes obesity.