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Facebook Launches Facebook Platform; They are the Anti-MySpace on 2007-05-23
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Applications: photos, groups, events. Plug into profiles. Use all the real connections people have
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Their photos app is by far the number one photo site on the internet.
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Events: similar story. 3x more ppeople invited to events thru facebook than evite.
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http://lap.umd.edu/poms/chapter8/chapter8.html on 2007-03-20
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Figure 8.4 shows the mean response time per selection as a function of the
number of alternatives. The lines show the predicted functions based on the
Hick-Hyman and Fitt's laws, and the points indicated the observed values. It
is clear that the log function fits the data quite well.
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The total response time is then given
by multiplying depth and response time
per menu frame as given from Equations 8.4 and 8.5:
t(N) = {(log N) / (log n)} (E(n) t +
k + c). 8.6
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Figure 8.4, however, shows only the response time per choice. Total time to
locate a target is given by the number of choices multiplied by the time per
choice. For a symmetric tree, the number of choices necessary to locate a
target is lognN, where N is the total number of terminal items
(4096). The response time per choice is given by Equation 8.5. Multiplying
these two results in
u(N) = (lognN)(c + klog(n)), or
u(N) = k(logN) + c(lognN). 8.15
The left hand term does not depend on the tree structure, only on the number of
terminal items. The right hand term gets smaller as n gets larger. The
result is that increased breadth of the tree reduces the overall response time.
The constant c, which indicates the time added per choice, determines
the magnitude of the effect. When c is large, increased depth becomes
more detrimental.
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The optimal breadth is quite sensitive to 1/f. For reasonable values
of reading time, key-press time, and computer response time, the optimal
breadth may increase substantially beyond 8 alternatives per frame.
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Using numerical methods, the optimum number of menu alternatives per frame was
determined for various combinations of the parameters for reading time,
key-press time and computer response time. These are shown in Table 8.1. What
is rather astounding about these tables is that within reasonable values for
the parameters the optimal number of alternatives per frame is between 4 and 7.
However, Lee and MacGregor's (1985) assumptions may be overly restrictive,
particularly for organized or highly familiar menus.
Paap and Hofstrand (1986) have extended the range of search strategies beyond
exhaustive and self-terminating menus to include any proportion of items that
need to be examined. They suggest that when searching well practiced menus or
when the alternatives in a menu are organized into categories, the scope of the
search may be substantially reduced. For a well practiced list, users may
learn approximately where to look for an item. Consequently, they need to scan
only a small portion of the total number of items. To account for this Paap et
al. introduce the parameter, 1/f, to indicate the proportion of items
that need to be read before the user terminates the search. The expected
number of items read is then:
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http://lap.umd.edu/POMS/Chapter9/Chapter9.html on 2007-03-20
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The superiority of the concave menu indicates that breadth is advantageous at
the top and bottom of the menu. The fact that increasing menu was
superior to the decreasing menu further indicates that breadth at the bottom is
of prime importance. It may be that a wide number of choices at the top
helps the user to formulate an idea for generating an item that meets the
conditions of the scenario and at the bottom the specific listing of
items may help to suggest a solution to the scenario. Furthermore, since
users generally get lost in the middle of the tree rather than at the beginning
or end, the concave menu reduces the probability of a wrong selection in the
middle of the tree.
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Finally, the concave menu (8x2x2x8) gives a broad range of choices at
the beginning, narrows in the middle, and then broadens at the end. The
concave menu has the advantage of search latitude at the beginning and end of a
path. If users redirect search locally or at the top of the menu, the concave
menu has a distinct advantage.
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The problem is that when items are clustered together in the menu hierarchy,
category names must be assigned to those sets of items. In many cases the
category names are not adequate descriptors of the subset. Categories such as
"Options," "Tools," "Windows," "Functions," fail to guide inexperienced users.
Menu frames provide insufficient information when:
(1) items within a cluster are not be adequately characterized by the category
name;
(2) the user infers that additional items are in a category; or
(3) category names overlap.
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