How performance of the ministers should be measured?

Its good that PMO has denied the permission of judging ministers by bureaucrats since bureaucrats themselves are corrupted. I think ministers should be judged based on their performance on different projects and public service by which the common population got benefited.

According to me minister's performances can be evaluated only on the basis of what he contributed for the development of the nation and for the social well being of the citizens of the country.

Ministers are not much different from other executives in the private sector;and both need pre-set goals/objectives to be their reference and indication of what is expected from them, and there should be a set of key performance indicators KPI's to help measure the performance, progress and achievement of these ministers.

Having said that, not all ministries are the same and definitely not all ministers are alike.  

-  There are "public service" ministries that are supposed to perform and deliver from day-1 and should continue to perform and maintain/sustain/grow/improve their performance in service of the public. This includes such sectors as education, health-care, finance/economy, energy, transportation, ... ... etc.

Other ministries are of special covering things as defense (MoD), secret service, security, .. etc.  And these ones are "by nature"not that visible - unless there is some sort of catastrophic event like war, terrorism, ..) and their services are required ad-hoc if needed/when needed.   The performance of these ministries will be more on special objectives without much of measurements and KPI's 

There should be a rating system which accounts everything that a minister does.

+ve point for the positives that he does, and -ve points for negatives that he does. 

And this rating system should be outsourced to a private organization for transparency and ingenuity.

The performance of the Ministers are difficult to monitor for the citizen except for the published outputs from News and Journals, which I think were misleading Indians for the past 50 odd years. Then the citizen need to evaluate on the basis of accurate information gathered analysed and printed. Nowadays we have websites where one should be able to get the data and information needed on this issue and the ministers should be willing to accept to the situation as it evolves. This requires a philosophy for runing the the nation which is missing and an objective and mission for the nation which is also missing. So monitoring ministers performance tantamount to hoodwinking citizen for their selinterest sake and the citizen who consider them as ideal forms follow in the same Machivellian intelligence route and lose on practical intelliengence.

the money they spent on the poorest of the poor

Ministership is an opportunity.  One should use it well.  PV Narasimha Rao was not good Prime Minister; nor was Vajpayee.  But PVN brought Manmohan Singh as Finance Minister.  This was genuinely a developmental initiative.  This should be the yardstick in which we should judge a minister.  In my view, Kapil Sibal is doing well.  He has really started many long term initiatives.  Chidambaram's taxation proposals were good although he was not there to implement them.  

All Ministers definitely do well in the short term, since that is what brings them immediate recognition.  They will surely ensure that there photographs are in streets!!

By analyzing non favouritism towards a particular community or group, consequences or long term effects and importance of past performance also age, enthusiasm and efforts for future ventures in the national interest, with having support in local region.

behing every politicians brain,there will be one super brain called his PA who even may be an IAS officer.if once, they are bought into limelight by methods of scrutiny, i think, the real work of any politician/minister will be known.