Talk:Z-factor

Comment
There is a z-factor for real gas compressibility which expresses the deviation from ideal behaviour of a gas when compressed. The Ideal gas formula P.V=n.R.T is reformulated to P.V=z.n.R.T where z is a variable dependant on the gas and the pressure. Several equations have been proposed for the calculation of z.

contact this person for expert advice
You say that this article requires expert attention. I suggest you contact zwu@stat.brown.edu since he / she has published on this topic. See Journal of Biomolecular Screening vol 12, page 229 (1997)

Abstract is free to all and is quoted here:

High-throughput screening is an essential process in drug discovery. The ability to identify true active compounds depends on the high quality of assays and proper analysis of data. The Z factor, presented by Zhang et al. in 1999, provides an easy and useful summary of assay quality and has been a widely accepted standard. However, as data analysis has undergone much improvement recently, the assessment of assay quality has not evolved in parallel. In this article, the authors study the implications of Z factor values under different conditions and link the Z factor with the power of discovering true active compounds. They discuss the different interpretations of Z factor depending on error distributions and advocate direct analysis of power as assay quality assessment. They also propose that in estimating assay quality parameters, adjustments in data analysis should be taken into account. Studying the power of identifying true “hits” gives a more direct interpretation of assay quality and may provide guidance in assay optimization on some occasions. (Journal of Biomolecular Screening 2007:229-234)

Rename
Should this page be renamed Z'-factor? See User talk:JohanNord. Geometry guy 22:07, 29 November 2010 (UTC)

I am copying the discussion mentioned above to here, for convenience. Melcombe (talk) 10:27, 30 November 2010 (UTC) .....

if we read the original article by Zhang et al 1999 (I have it here in front of me), the title of the page Z-factor should really be Z'-factor, because that is what the equations in the definition-section on the page describes. In the paper by Zhang et al, a Z factor is also defined, and this is different from the Z-prime factor. So you see, the flawed contents of this page is page is extra misleading. It is therefore important that that the title of the page (and the text) is correct so that the contents is not confused with the definition of the real Z factor! Thus, according to Zhang et al:
 * $$\text{Z-prime factor} = 1 - {3 (\sigma_p + \sigma_n) \over | \mu_p - \mu_n |}.$$

while,
 * $$\text{Z-factor} = 1 - {3 (\sigma_s + \sigma_c) \over | \mu_s - \mu_c |}.$$

where s denotes sample and c control.
 * Question, how do we change this? Can you as "editor" change the title of the page, or do we for example create a new page called Z' factor and copy the current article there and make the current page a stub with only a little bit of text referring to the original article? —Preceding unsigned comment added by JohanNord (talk • contribs) 23:39, 28 November 2010 (UTC)
 * Welcome to Wikipedia. If you believe the article is incorrect, please edit it! If you would like the opinion of an expert on the subject, I suggest contacting User:Michael Hardy. Thanks, Geometry guy 09:17, 29 November 2010 (UTC)
 * The "move" tab on the article page can be used to "move" (i.e., rename) the article to a new title. Racepacket (talk) 14:16, 29 November 2010 (UTC)

There two questions here. Can the "prime" used by Zhang be reasonably interpreted as just distinguishing two different versions of the same thing, so the article is really about a way of constructing a measure of difference that can be applied in different ways? How other people actually using the term, as this is really the determining thing. The second reference in the article, of which I can see only the abstract, only mentions Z-factor in the abstract with any specifics, so it may be using "Z-factor" to cover a multitude of different contexts. Of course, an entirely different, possibly more intrinsically meaningful, name might be appropriate .... after all it is just a variation on a signal to noise ratio. Does it have enough importance even to be counted as notable ... there is as yet only one supposedly independent citation for its use. Melcombe (talk) 10:27, 30 November 2010 (UTC)
 * I'm lucky enough to be able to see the full text of Sui & Wu (2007) thanks to my employer, and it does suggest this could be notable:

"Since its introduction, the Z factor criterion has become the most widely used parameter in the evaluation and validation of HTS [high-throughput screening] experiments. The publication of Zhang et al. is one of the most cited papers in HTS. Large laboratories, including the National Institutes of Health Chemical Genomics Center (http://ncgc.nih.gov) and the National Screening Laboratory for the Regional Centers of Excellence in Biodefense and Emerging Infectious Diseases (http://nsrb.med.harvard.edu), recommend Z ≥ .5 as an indication of proper assay optimization. In a recent publication, Iversen et al.[J Biomol Screen 2006;11:247-252] conducted a simulation study and compared the performance of the Z factor to that of the signal window and assay variability ratio and recommended Z factor as a preferred assay performance measure.

There is no doubt about the usefulness and popularity of the Z factor."

- Y. Sui & Z. Wu
 * Afraid I can't quite be bothered to add something of this to the article just at the moment myself though. --Qwfp (talk) 19:54, 30 November 2010 (UTC)

Broken link
The link to unpublished document listed under further reading is broken because the document has moved. I don't know if it is worth updating the link or it would be better to just delete it: it's just a one-page document, and could move again. JS Hoyer (talk) 16:59, 12 January 2013 (UTC)
 * 1) Old link: http://iccb.med.harvard.edu/screening/Quantitative%20Assay%20Evaluation%20and%20Optimization%20complete%20(3).pdf
 * 2) New link: http://iccb.med.harvard.edu/wp-content/uploads/2012/02/Quantitative-Assay-Evaluation-and-Optimization-complete-3.pdf