- Google Scholar is the most complete. Nearly all your contributions appear there automatically!!

- ISI is the most faithful, but some papers and citations are missed.

- Scopus is better organized, but some papers and citations are missed.

Therefore, to define a single indicator, h index calculated by Google Scholar may be a good and simple one.

My preferences for citation analysis are Scopus and Google Scholar. Scopus information is better designed, and well laid out than Google Scholar. Both are easy to access. However, the data from Google Scholar are more up to date than those from Scopus. For example, Google Scholar captured nearly all my referee journal publications, while Scopus captured only 80%. More seriously, one of my top 20 publications from Google Scholar was missing completely from my list of Scopus citations. Also, very interestingly, my citation data were much higher on Google Scholar. The differences were HUGE : Ranging from 7-49 citations higher on Google Scholar than on Scopus for my top 20 publications. Consequently, my h-index was clearly 4 points higher on Google Scholar than on Scopus. This example highlights the need for universities and other research agencies to regularly scrutinize the integrity of the data generated by the various indexing services.

For reliable information on impact factors of journals, I always find ISI useful.

Google scholar has a problem It picks the citation from databases that are only available to them. They do not cater for other databases.

This is the answer which I got from Google Scholar

"We are sorry to learn that we are not counting all the citations to your papers.

If a publisher doesn't give us metadata about their articles' citations, we use an automated algorithm to extract citations from their articles. This automated algorithm isn't perfect and can make mistakes. We're currently not able to fix missing citations on a one-off basis, but we do use examples like the ones you provided as we continue to improve the citation extraction algorithm"

Scopus is relatively better but slower.

It depends what your university or national council or agency use for evaluation. If you want to know all your citations perhaps google scholar is better because it includes many citations from books, articles and reports in the web. However, it could include many not peer review documents. This is the difference with ISI that all the journal in the index have to have some quality parameters. In my case the national council only accept papers and citations from ISI.

Both r good and interestingly the journals with good impact factors will naturally have good h index value.

PUBLISH OR PERISH software is one the better tools to evaluate the research metric. Its easily downloadable and free.

Recently h index gained more popularity to evaluate one's research value.

All scopus indexed journals will have h index value.

Both are good. I use scopes most of the time siply due to easy access

scopes is general, ISI indexing the the journal with high impact factor under ISI-JCR.

So if you looking for higher quality, go to ISI.

- Google Scholar is the most complete. Nearly all your contributions appear there automatically!!

- ISI is the most faithful, but some papers and citations are missed.

- Scopus is better organized, but some papers and citations are missed.

Therefore, to define a single indicator, h index calculated by Google Scholar may be a good and simple one.

So far in ISI nothing missed, ISI papers are select able based on ISI recognition, that's why not all citation counted in ISI.

ISI count ISI citation only.

Some publications not considered to be listed in ISI-index are still available in Scopus. Therefore publications in ISI-Index journal have higher quality than those in Scopus.

That is:

1. ISI (high impacts)

2. SOUPS

3. Google (very wide, mixed quality)

I tend to agree with those colleagues who argued that there is no best (meaning absolute) evaluation. As we all know, assessment schemes are based on different assumptions and express different values. Journals have their (multi-year) citation indices or impact factors, and there are several alternative metrics for articles. The impact factors of journals are not necessarily related to the citation or impact of an article therein. That is why several journals started publishing specific article-level metrics. Anyway, these all are highly discipline-dependent. As I see there are at least as many advocates as opponents of h-index. The ‘h-index article’ on Wikipedia offers a good comparison of the bases of calculation and points at many issues. I think, though completely different, c-index and RG-s are based on competitive ideas.

For wide coverage and of reasonable quality articles SCOPUS indexing provides better evaluation

Well, the two are more or less the same in assessing scholars' publications

Probably you are thinking about applying to some organism that will evaluate your research. In this case, the question should be: which database are using them? In my country (Spain), Portugal, and others, the response is ISI-JCR but if you ask me for my personal opinion, I prefer Scopus. Anyway, the "organisms" put the rules. Not us.

I do not recommend google scholar because it includes "low quality references" (such as webpages), and it also mixes references from several different researchers. Specially if your surname is quite "popular" (several people having the same surname). Some people enjoy this database because it provides higher figures than the others, but I think that this is due to inaccuracies of the system.

1.Scopus ,2. ISI , 3. Google

google scholar follows everything. Also nowdays you can make profile there and get email information about your citation. But scopus is more realistic I think. For particle physicists HEP is interesting

http://inspirehep.net/

There is also Scirus. Sometimes citing (my research) papers first appear in Scirus, sometimes in Google Scholar. Usually, they appear much later in Scopus and ISI. However, so far, the only officially accepted index (used for evaluation when you apply for a grant or position) is ISI. And another thing. Out of these 4 data bases, only two are freely available (Google and Scirus). Both Scopus and ISI require subscription. Sometimes, Editors of the Elsevier journals provide you with a free access to Scopus (for 30 days), if you agree to review the submitted to them paper. But I've never heard about such a courtesy from American journals regarding a limited free access to ISI index.

http://www.scirus.com/srsapp/

Research impact will always changing. Hopefully, every 20 years.

Colleagues, you can read this on Wikipedia: "Scirus was a comprehensive science-specific search engine. Like CiteSeerX and Google Scholar, it was focused on scientific information. Unlike CiteSeerX, Scirus was not only for computer sciences and IT and not all of the results included full text. .... Scirus was owned and operated by Elsevier. [1] In 2013 an announcement appeared, on the Scirus homepage, announcing the sites retirement in 2014. We are sad to say goodbye. Scirus is set to retire in early 2014. An official retirement date will be posted here as soon as it is determined." I observed that since February 2014 there is no service on the Scirus homepage.

Different universities subscribe to different indexing services and it is easy to find about author or a paper through university subscriptions.

For good economic ( social sciences) journals, they are indexed both in Scopus and SSCI ( ISI). But a significant number of jounals are indexed in Scopus but not SSCI and many among them are not good journals

Here we are again discussing indexing. I want others, especially my peers, to read and cite my works. So I go for a clear-cut avenue that provide this at a point in time - Scopus and H-index will definitely reveal your work to,the needies. 

Are the impact factors from international scientific indexing (ISI) are of same value like those by ISI Thomson Reuters ?

I don't think that any index alone can do the job, but by consulting several, you get quite a clear picture.

ISI and Scopus are in a group and do not involve all publications but insist on Journal recognition, but Google Scholar is unique.

Both of them present a good evaluation of papers.

I also use "Publish and Perish" to evaluate my scientific output.

HI Ewa, 

Please check with http://scholarlyoa.com/publishers/ and http://scholarlyoa.com/individual-journals/ 

before you send your manuscripts to some potential predatory journals and publishers

 Be careful, although a nubmer of journals are indexed by SCOPUS or even ISI ( SCI, SCIE, SSCI or AHCI), some among them  are predatory journals, so please avoid them. 

Please check with http://scholarlyoa.com/individual-journals/ and http://scholarlyoa.com/publishers/

Some journals use the famous university such as " The Business Review, Cambridge" to attract more atuthors and trick authors out of publication fee but in fact they are a predatory journal, according to Beall's list.

I used Scopus in a recent Bibliometric study on Portuguese research in e-government because it offers a broader coverage of publicarmos no the subject. 

HTTPS:://www.researchgate.net/publication/268212619_Bibliometric_Analysis_of_Portuguese_Research_in_e-government

Article Bibliometric Analysis of Portuguese Research in e-government

Yes, we can use other indexing services, but overall ISI is the best

SCOPUS is not showing the citations of NON-SCOPUS indexed paper on Author account.

I also see the trend concerning Scopus that Dr. Radhakrishna mentioned. I think handling open access journals and subscription-based journal according to same quality criteria and similar measures is a current issue. It is difficult to achieve 100 percent reliability of the paper citation indices and the journal (multi-year) impact factors. ISI is still doing well.

I too agree with Dr Vangipuram Radhakrishna and DR Imre Horvath.  The review process is bit lengthy in the case of SCI indexed Journals.  The reputation of those journals is also very high. SCOPUS, DBLP, Google Scholar follows later only.

I do agree with Prof. Pedro.

Oh not, googlescholar covers a lot of really bad journals, including predatory journals. 

Furthermore, according to my best knowledge, GoogleScholar does not exclude self-references and affiliated references.

Concern to SCOPUS indexing ,standard of evaluating procedure is high. This may put ahead but no global unique procedure for evaluating index

As I proved that Scopus contains a lot of predatory journals, submission fee and open access withou peer-review or with fake review.

Both are commercial, a best alternative is redalyc.org.

Is there anything that is not commercial at the bottom?

Isi

of course ISI 

I prefer ISI to Scopus

Yes, I do agree with you

If of interest a short note about this topic.

Best

Gil

Working Paper The indexation of scientific journals and the bibliometry: e...

 Scopus could be the average rank which is closer to ISI which is higher. But may of researcher don't have the access to check if it is ISI or not.

 I think ISI and Scopus are more faithful than Google Scholar, but the problem not all researchers have access to them

SCOPUS have a higher rate then ISI

SCOPUS indexed journals are widely accepted by our researchers and most of the universities

Yes it is the case in many countries in France it is the case

It depends on individual choice of evaluation, some prefer one than the other (SCOPUS/ISI).