Fold change is a measure describing how much a quantity changes between an original and a subsequent measurement. It is defined as the ratio between the two quantities; for quantities A and B, then the fold change of B with respect to A is B/A. Fold change is often used when analysing multiple measurements of a biological system taken at different times as the change described by the ratio between the time points is easier to interpret than the difference.
Fold change is so called because it is common to describe an increase of multiple X as an 'X-fold increase'. As such, several dictionaries, including the Oxford English Dictionary[1] and Merriam-Webster Dictionary,[2] as well as Collins's Dictionary of Mathematics, define '-fold' to mean 'times', as in '2-fold' = '2 times' = 'double'. Likely because of this definition, many scientists use not only 'fold', but also 'fold change' to be synonymous with 'times', as in '3-fold larger' = '3 times larger'.[3][4][5] More ambiguous is fold decrease, where, for instance, a decrease of 50% between two measurements would generally be referred to a 'half-fold change' rather than a '2-fold decrease'.[citation needed]
Fold change is often used in analysis of gene expression data from microarray and RNA-Seq experiments for measuring change in the expression level of a gene.[6] A disadvantage and serious risk of using fold change in this setting is that it is biased[7] and may misclassify differentially expressed genes with large differences (B − A) but small ratios (B/A), leading to poor identification of changes at high expression levels. Furthermore, when the denominator is close to zero, the ratio is not stable, and the fold change value can be disproportionately affected by measurement noise.
Alternative definition[edit]
There is an alternative definition of fold change,[citation needed] although this has generally fallen out of use. Here, fold change is defined as the ratio of the difference between final value and the initial value divided by the initial value. For quantities A and B, the fold change is given as (B − A)/A, or equivalently B/A − 1. This formulation has appealing properties such as no change being equal to zero, a 100% increase is equal to 1, and a 100% decrease is equal to −1. However, verbally referring to a doubling as a one-fold change and tripling as a two-fold change is counter-intuitive, and so this formulation is rarely used.
Step 1: In the given prism, the base is a rectangle, two of the side walls are triangles and other two side walls are rectangles. So, the given prism is a triangular prism. Step 2: Volume of a triangular prism = (1/2) x base area x height. V = (1/2) x b x h. Step 3: Find base area. Base area = l x w. Base area = 528. What is Meant by the Volume of a Rectangular Prism? In mathematics, the prism is a three-dimensional figure in which the faces of the solid are rectangles. It has six rectangular faces. The rectangular prism is also known as the cuboid. It has a rectangular cross-section. The opposite faces of the rectangular prism are of equal measure.
This formulation is sometimes called the relative change and is labeled as fractional difference in the software package Prism.[8]
Fold changes in genomics and bioinformatics[edit]
In the field of genomics (and more generally in bioinformatics), the modern usage is to define fold change in terms of ratios, and not by the alternative definition.[9][10]
However, log-ratios are often used for analysis and visualization of fold changes. The logarithm to base 2 is most commonly used,[9][10] as it is easy to interpret, e.g. a doubling in the original scaling is equal to a log2 fold change of 1, a quadrupling is equal to a log2 fold change of 2 and so on. Conversely, the measure is symmetric when the change decreases by an equivalent amount e.g. a halving is equal to a log2 fold change of −1, a quartering is equal to a log2 fold change of −2 and so on. This leads to more aesthetically pleasing plots, as exponential changes are displayed as linear and so the dynamic range is increased. For example, on a plot axis showing log2 fold changes, an 8-fold increase will be displayed at an axis value of 3 (since 23 = 8). However, there is no mathematical reason to only use logarithm to base 2, and due to many discrepancies in describing the log2 fold changes in gene/protein expression, a new term 'loget' has been proposed.[11]
Properties of a Rectangular Prism: A rectangular prism has 8 vertices, 12 sides and 6 rectangular faces. All the opposite faces of a rectangular prism are equal. A rectangular prism has a rectangular cross section. Rectangular prisms can be of two types, namely right rectangular prism and non-right rectangular prisms. A rectangular prism with a length (L) of 2 a width (W) of 3 and a height (W) of 4 has a volume (V) of 24. A cube has three equal sides (S), this means the volume can be determined by multiplying Side x Side x Side, this is the same as Side 3.
See also[edit]
Notes[edit]
- ^'Free OED – Oxford English Dictionary'.
- ^'Definition of TWOFOLD'.
- ^Cieńska, M.; Labus, K.; Lewańczuk, M.; Koźlecki, T.; Liesiene, J.; Bryjak, J. (2016). 'Effective L-Tyrosine Hydroxylation by Native and Immobilized Tyrosinase'. PLOS One. 11: e0164213. doi:10.1371/journal.pone.0164213. PMC5053437. PMID27711193.
- ^Cunningham, M. W. Jr.; Williams, J. M.; Amaral, L.; Usry, N.; Wallukat, G.; Dechend, R.; LaMarca, B. (2016). 'Agonistic Autoantibodies to the Angiotensin II Type 1 Receptor Enhance Angiotensin II–Induced Renal Vascular Sensitivity and Reduce Renal Function During Pregnancy'. Hypertension. 68: 1308–1313. doi:10.1161/HYPERTENSIONAHA.116.07971. PMC5142826. PMID27698062.
- ^Li, B.; Li, Y. Y.; Wu, H. M.; Zhang, F. F.; Li, C. J.; Li, X. X.; Lambers, H.; Li, L. (2015). 'Root exudates drive interspecific facilitation by enhancing nodulation and N2 fixation'. PNAS. 113 (23): 6496–6501. doi:10.1073/pnas.1523580113. PMC4988560. PMID27217575.
- ^Tusher, Virginia Goss; Tibshirani, Robert; Chu, Gilbert (2001). 'Significance analysis of microarrays applied to the ionizing radiation response'. Proceedings of the National Academy of Sciences of the United States of America. 98 (18): 5116–5121. doi:10.1073/pnas.091062498. PMC33173. PMID11309499.
- ^Mariani, T. J.; Budhraja V.; Mecham B. H.; Gu C. C.; Watson M. A.; Sadovsky Y. (2003). 'A variable fold change threshold determines significance for expression microarrays'. FASEB J. 17 (2): 321–323. doi:10.1096/fj.02-0351fje. PMID12475896.
- ^'Prism'. www.graphpad.com. Retrieved 2018-06-07.
- ^ abRobinson, M. D.; Smyth, G. K. (2008). 'Small-sample estimation of negative binomial dispersion, with applications to SAGE data'. Biostatistics. 9 (2): 321–332. doi:10.1093/biostatistics/kxm030. PMID17728317.
- ^ abLove, M. I.; Huber, W.; Anders, S. (2014). 'Moderated estimation of fold change and dispersion for RNA-seq data with DESeq2'. Genome Biology. 15: 550. doi:10.1186/s13059-014-0550-8. PMC4302049. PMID25516281.
- ^Pacholewska, Alicja (2017). ''Loget' – a Uniform Differential Expression Unit to Replace 'logFC' and 'log2FC''. Matters. doi:10.19185/matters.201706000011. ISSN2297-8240.
External links[edit]
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Fold_change&oldid=978913748'
In a 3-D figure, if the base is a rectangle or square, two of the side walls side walls are triangles and other two side walls are rectangles or squares, then the 3-D figure is called triangular prism.
Any triangular prism will look like the one shown below.
The formula to find volume of the above triangular prism is
= (1/2) x Base area x Height
Important Note :
The above formula will work only if the given figure meets the following conditions.
(i) The base must be a rectangle or square.
(ii) Two of the side walls side walls must be triangles
(iii) Other two side walls must be rectangles or squares.
Examples
Example 1 :
Prism 8 3 1 Equals Inches
Find the volume of the prism.
![Prism Prism](https://hi-static.z-dn.net/files/d23/e472c39be79e637d3b64def84f93d6d1.jpg)
Solution :
Step 1 :
In the given prism, the base is a rectangle, two of the side walls are triangles and other two side walls are rectangles.
So, the given prism is a triangular prism.
![Inches Inches](https://i1.sndcdn.com/artworks-000662116531-r98izi-t500x500.jpg)
Step 2 :
Volume of a triangular prism = (1/2) x base area x height
or
V = (1/2) x b x h
Step 3 :
Find base area
Base area = l x w
Base area = 528
Base area = 528 sq.m
Step 4 :
Find volume of the triangular prism
V = (1/2) x b x h
V = (1/2) x (528) x 7
V = 1848 cubic meters.
So, the volume of the given prism is 1848 cubic meters.
Example 2 : System toolkit 2 2 1 – advanced system maintenance.
Bradley’s tent is in the shape of a triangular prism shown below. How many cubic feet of space are in his tent ?
Solution :
Step 1 :
To find the number of cubic feet of space in Bradley’s tent, we have to find the volume of his tent.
Step 2 :
Volume of a triangular prism = (1/2) x base area x height
or
V = (1/2) x b x h
Find base area
Base area = l x w
Base area = 9 x 6
Prism 8 3 1 Equals The Square Root
Base area = 54 sq.ft
Step 4 :
Find volume of the triangular prism
V = (1/2) x b x h
V = (1/2) x (54) x 4
V = 108 cubic.ft
So, the number of cubic feet of space in Bradley’s tent is 108.
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