-
Egghe, L.: ¬A noninformetric analysis of the relationship between citation age and journal productivity (2001)
0.01
0.013378119 = product of:
0.026756238 = sum of:
0.026756238 = product of:
0.053512476 = sum of:
0.053512476 = weight(_text_:x in 5685) [ClassicSimilarity], result of:
0.053512476 = score(doc=5685,freq=2.0), product of:
0.19116588 = queryWeight, product of:
4.2226825 = idf(docFreq=1761, maxDocs=44218)
0.045271195 = queryNorm
0.27992693 = fieldWeight in 5685, product of:
1.4142135 = tf(freq=2.0), with freq of:
2.0 = termFreq=2.0
4.2226825 = idf(docFreq=1761, maxDocs=44218)
0.046875 = fieldNorm(doc=5685)
0.5 = coord(1/2)
0.5 = coord(1/2)
- Abstract
- A problem, raised by Wallace (JASIS, 37,136-145,1986), on the relation between the journal's median citation age and its number of articles is studied. Leaving open the problem as such, we give a statistical explanation of this relationship, when replacing "median" by "mean" in Wallace's problem. The cloud of points, found by Wallace, is explained in this sense that the points are scattered over the area in first quadrant, limited by a curve of the form y=1 + E/x**2 where E is a constant. This curve is obtained by using the Central Limit Theorem in statistics and, hence, has no intrinsic informetric foundation. The article closes with some reflections on explanations of regularities in informetrics, based on statistical, probabilistic or informetric results, or on a combination thereof
-
Egghe, L.: New relations between similarity measures for vectors based on vector norms (2009)
0.01
0.013378119 = product of:
0.026756238 = sum of:
0.026756238 = product of:
0.053512476 = sum of:
0.053512476 = weight(_text_:x in 2708) [ClassicSimilarity], result of:
0.053512476 = score(doc=2708,freq=2.0), product of:
0.19116588 = queryWeight, product of:
4.2226825 = idf(docFreq=1761, maxDocs=44218)
0.045271195 = queryNorm
0.27992693 = fieldWeight in 2708, product of:
1.4142135 = tf(freq=2.0), with freq of:
2.0 = termFreq=2.0
4.2226825 = idf(docFreq=1761, maxDocs=44218)
0.046875 = fieldNorm(doc=2708)
0.5 = coord(1/2)
0.5 = coord(1/2)
- Abstract
- The well-known similarity measures Jaccard, Salton's cosine, Dice, and several related overlap measures for vectors are compared. While general relations are not possible to prove, we study these measures on the trajectories of the form [X]=a[Y], where a > 0 is a constant and [·] denotes the Euclidean norm of a vector. In this case, direct functional relations between these measures are proved. For Jaccard, we prove that it is a convexly increasing function of Salton's cosine measure, but always smaller than or equal to the latter, hereby explaining a curve, experimentally found by Leydesdorff. All the other measures have a linear relation with Salton's cosine, reducing even to equality, in case a = 1. Hence, for equally normed vectors (e.g., for normalized vectors) we, essentially, only have Jaccard's measure and Salton's cosine measure since all the other measures are equal to the latter.
-
Egghe, L.: ¬A universal method of information retrieval evaluation : the "missing" link M and the universal IR surface (2004)
0.01
0.009200432 = product of:
0.018400865 = sum of:
0.018400865 = product of:
0.03680173 = sum of:
0.03680173 = weight(_text_:22 in 2558) [ClassicSimilarity], result of:
0.03680173 = score(doc=2558,freq=2.0), product of:
0.15853201 = queryWeight, product of:
3.5018296 = idf(docFreq=3622, maxDocs=44218)
0.045271195 = queryNorm
0.23214069 = fieldWeight in 2558, product of:
1.4142135 = tf(freq=2.0), with freq of:
2.0 = termFreq=2.0
3.5018296 = idf(docFreq=3622, maxDocs=44218)
0.046875 = fieldNorm(doc=2558)
0.5 = coord(1/2)
0.5 = coord(1/2)
- Date
- 14. 8.2004 19:17:22
