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I find the AB index and ranking very useful as a mark of my progress in the hobby. But I do have a few questions and observations and I wonder if people on this Forum could help me. I apologise if all these things have been brought up (and answered) before. I couldn't find anything on this Forum. 1) How exactly is the AB index calculated? Since I don't understand Javascript [or whatever language it is] I can't get in from the reference to the code. The reason I ask this that - in order to keep my images to a manageable number, I regular delete older images. But this has resulted in changes to my AB index (both up and down). Perhaps I should simply keep all my images on AB. [But I am mindful of the cost of storage]. 2) Is there a code of practice for managing one's image collection to avoid attempts to manipulate one's AB index? Or is it OK to do so? [As a side note I noticed that I recently "lost" 10 Top Pick nominations in my stats. I presume this was due to a re-calculation of the TP/IOTD numbers to avoid double counting i.e. a nomination for TP wasn't recorded as such if is also became a TP.] 3) There are a number of accounts (including observatories) whose high AB index is solely driven by the large number of [well-deserved] likes to a small number of images made as part of a large collaboration. This seems at odds with the stated goal of the AB index i.e. to give an indication of one's abilities and activity level in astrophotography. 4) AB index is also described to be non-inflationary, but AB indexes continue to rise. This is not a bad thing - indeed it must reflect growing activity levels - something to be encouraged. Staying at the same numerical AB index will see one slowly sink in the rankings. That is a also good thing, since it encourages a person to be active. But, at the same time, a long-time highly competent user can be "demoted" in the rankings by a first-time submitter as part of a large collaboration. 5) It could reasonably be argued that this is a small issue and there is nothing to worry about it. But it may be worth considering if one's AB index is manipulatable or if the growing number of large collaborations is leading to significant anomalies in the rankings. AB is, of course, not alone in these challenges. In research, well-used citation statistics like the H-index [which does avoid the low publication problem] is still influenced by "large collaboration" issue. It may seem presumptuous of someone who doesn't really understand the AB index to make these observations. Indeed, it may well be that the AB index already accounts for some of these issues raised. If so, I will happily be corrected. Either way, I will continue to use the AB index and my ranking as a reflection of progress [or otherwise] against my peers. Thank you Brian |
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Brian Boyle: It's hard to explain without mentioning code or maths, but the simplest way is this: Step 1: calculate the average likes of your images Step 2: take into considerationon only images with number of likes greater than the average, ignore the others Step 3: calculate the index as the average number of likes of images in Step 2 multiplied by the logarithm of the number of images being considered This results in a number that depends on how many images you have, and how many likes they have. Btw, some details are on this page: https://welcome.astrobin.com/features/image-index Brian Boyle: Please please please don't do that! I'm extremely happy to pay the storage bill. That's one of AstroBin's smaller costs! AstroBin's entire community benefits from having images on the platform. This is why AstroBin doesn't delete your images if you stop paying for a subscription: there's value for the community in them, and that gives AstroBin a raison d'etre. Brian Boyle: The only thing would be the guideline about posting edits as revision rather than new images (revision's don't get their own likes): https://welcome.astrobin.com/features/image-revisions#faq However this is not realistic for me to enforce. Brian Boyle: Yes, that's right. AstroBin now only assigns badges once their final, so images who reached a Top Pick status lost their Top Pick nomination status. That was a mistake to begin with. Brian Boyle: I don't think that was ever the goal of the Index. Intially it was a spam prevention measure, and I can't remember when or how I asked a mathematician friend of mine to help with an algorithm to design a ranking system based on likes. More than anything, the AB Index is a popularity context. I'm not ashamed to say that it doesn't really have a pretense of measuring an astrophotographer's worth, in my opinion! Sure, by the big picture, there's surely a correlation between the likes and how good one's photographs are, but this correlation may get lost in the noise when it comes to being socially active and garnering likes by means of popularity. Collaborations were added much later and I had to decide if to include them in the various stats. It made sense to include them, so I did it for the Index too. Brian Boyle: By non-inflationary I mean that it doesn't grow by itself if you do nothing. In fact, you can lose Index just as well. I hope this clarifies a bit  Thanks for the questions! Salvatore |
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Salvatore Iovene: It's not quite fair, if I may add my three pennies. My lack of activity is not because I don't want - it's because I CANNOT. My location and the British weather don't allow me to image, six images only since June and believe me, I bring out my stuff even for a few hours between clouds or even rain. In the meantime, some followed imagers upload new pics nearly every day. It would be fair to add to the algorithm a factor of the location with its probability of clouds and rain. Martha. |
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Thanks for the background @Salvatore Iovene I hadn't realised that the strong preference was to retain all images on AB. Is there any way I can reinstate my deleted images? |
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Brian Boyle: Sure, they're in your trash! Go yo your gallery, open the View menu, choose Trash. Then select the images you want to restore, and click the Restore button |
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Salvatore Iovene:Brian Boyle: Thanks. I am now restoring some happy memories to my [visible] AB account. |
