An updated version of the Rio scale was recently proposed: Forgan, Wright, Tarter, Korpela, Siemion, Almár, and Piotelat 2018 Rio 2.0: revising the Rio scale for SETI detections | International Journal of Astrobiology | Cambridge Core It follows the original one in having (quality)x(reliability), but its quality scale is revised and its reliability scale is much expanded. All the descriptive text is quotes from the article, with correction of a few typos, but the formatting is mine, and I have restated the algorithms. In summary:

• Quality
  • What is the estimated distance to the source of the signal?
  • What are the prospects for communication with the source of the signal?
  • Is the sender aware of humanity/its technology?
• Reliability
  • How real and amenable to study is the phenomenon?
  • How certain are we that the phenomenon is not instrumental?
  • How certain are we that the phenomenon is not natural or anthropogenic?

Here is the calculation of that scale, explained in more detail.

The quality Q is calculated from three parts, with scores Q1, Q2, and Q3:

• Q1: What is the estimated distance to the source of the signal?
  • 4: Less than a light day (i.e. in the Solar System)
  • 3: Light-days to light-years (i.e. about as close as the nearest star)
  • 2: Light-years to tens of light-years
  • 1: Hundreds to thousands of light-years (in the Galaxy)
  • 0: Longer/unknown
• Q2: What are the prospects for communication with the source of the signal?
  • 4: We are in the active two-way communication
  • 3: We could respond using the same medium/encoding as the signal within 20 years
  • 2: We can understand the signal or we have artifacts we can study
  • 0: No communication is taking place
• Q3: Is the sender aware of humanity/its technology?
  • 2: Yes, certainly – the signal is intended for us, specifically
  • 1: Possibly, but there is a little or no evidence for this
  • 0: Almost certainly not (e.g. they are too far away)
  • -1: Senders are apparently extinct

Once these are calculated, one finds Q = max(Q1 + Q2 + Q3, 0).

The reliability comes in three parts, with scores J1, J2, and J3.

The first part, with subscores J1.1, J1.2, and J1.3, is for: How real and amenable to study is the phenomenon?

• J1.1: Is there a significant uncertainty about whether the phenomenon occurred/occurs at all? For instance, are the data corrupted, is there a significant risk of misunderstanding or transcription error? ‘Significant’ here means more than 10%.
  • 6 (skip the rest): Yes, there is a significant uncertainty
  • 7: No, something almost certainly happened
• J1.2: How amenable to study is the phenomenon?
  • 0: The phenomenon has been observed exactly once (e.g. the Wow! signal).
  • 1: The phenomenon has been observed a small but plural number times, either as multiple targets showing similar phenomena, or a single target showing multiple similar events.
  • 2: The phenomenon has been confirmed to be real and repeated, for instance by multiple groups using a single instrument to observe the phenomenon or by an additional observation with a different instrument or from a different site.
  • 3: The phenomenon is observed routinely by different groups using different equipment.
• J1.3: Is the discoverer of the phenomenon the same person/group that predicted that such a phenomenon would indicate the presence of alien intelligence?
  • -1: The claimants predicted the phenomenon they have ‘discovered’.
  • 0: The claimants have identified a new phenomenon, or one predicted by others.

One then finds the total first score J1 = J1.1 + J1.2 + J1.3.

The second part, with subscores J2.1 and 2.2, is for: How certain are we that the phenomenon is not instrumental?

• J2.1: Does the phenomenon look like a known instrumental or psychological effect?
  • 0 (skip the rest): Yes. (me: lens flares, subjective pattern-finding, …)
  • 7: No.
• J2.2: What chances do the instrument builders/experts in the method/observers of the phenomenon give that the signal is not instrumental?
  • 0: These experts have not weighed in at all.
  • 1: These experts give a ∼90% chance that it is instrumental (so a ∼10% it is real).
  • 2: These experts give even odds that it is instrumental.
  • 3: These experts give <10% chance that it is instrumental.

One then finds the total second score J2 = J2.1 + J2.2.

The third part, with subscores J3.1 and J3.2, is for: How certain are we that the phenomenon is not natural or anthropogenic?

• J3.1: Is there a good reason to think the phenomenon is a hoax?
  • 0 (skip the rest, “end quiz”): Yes.
  • 1: No.
• J3.2: How does a wide community of experts assess the probability that there are any known sources of natural or anthropogenic signal that could explain the phenomenon?
  • 0: A wide range of experts agree that the signal is clearly natural/anthropogenic, or said experts have not been consulted.
  • 1: It is consistent with a common phenomenon.
  • 3: It is consistent only with a rare or poorly understood phenomenon.
  • 6: It is not consistent with any known natural or anthropogenic phenomena (but unknown natural/anthropogenic phenomena could still be the cause).
  • 8: Only extraterrestrial, artificial explanations make sense (i.e. those requiring non-human design and engineering, for instance: a Dyson sphere, a narrow band carrier wave from an extraterrestrial source, a strictly periodic pulsed laser; in other words: all natural and anthropogenic explanations been ruled out).
  • 9: The phenomenon contains information content of clearly intelligent design (i.e. it contains a message; or is an obviously artificial and alien artefact available for close – perhaps robotic – inspection).

One then finds the total third score J3 = J3.1 + J3.2.

Once one finds these three scores, one finds the total reliability score R = J1 + J2 + J3 – 20.

Then D = 10^(J-10)/2,

and then the final score R = Q*D.

The authors have these interpretations of quality scores Q:

• 10: Revolutionary. Everyday life on the Earth will change forever.
• 8 – 9: The making of an epoch; the future direction of humanity is changed.
• 6 – 7: SETI becomes the ‘study of ETI’. There are good prospects for near-future, limited understanding of ETI.
• 4 – 5: Scientifically revolutionary, but of no everyday consequence. Prospects for understanding ETIs remain decades in the future.
• 0 – 3: Philosophically ground-breaking, but of limited immediate social or scientific impact. The prospects for understanding ETIs remain unclear.

They have these interpretations of reliability scores J:

• 10: Aliens. Front page of every major newspaper.
• 9: Significant mainstream press interest warranted, heavy coverage by technical popular press. Broad agreement that the signal could be due to aliens.
• 7 – 8: SETI interest definitely warranted; technical popular press interest probably warranted; possible off-beat news item for general press, if expressed with appropriate caveats. If not aliens, still very interesting.
• 5 – 6: SETI interest probably warranted; technical popular press interest potentially warranted.
• 1 – 4: SETI interest potentially warranted; no press interest warranted.
• < 1: No interest warranted.

For overall scores R, they continue to use the interpretations in the original Rio scale.