# Statistics

Willem Ferguson willemferguson at zoology.up.ac.za
Tue Aug 22 03:24:20 PDT 2017

```On 21/08/2017 18:18, Tomaz Canabrava wrote:

Willem,

See if this image is better.

Got this, thank you very much. It looks extremely promising: the
presentation style looks extremely acceptable.

Question 1. Beneath each blue bar for Depth and Temperature is a thin
(grey?) horizontal line. What does this indicate? For temperature it always
corresponds to a value of zero °C. For Depth it corresponds to a value of
between 0 and 15.

Question 2. The vertical positions of the blue bars in each column, what do
they signify? For instance, the leftmost bar for temperature (a trip to
Hoodsport) indicates around 45 (°F ?? = ~7 °C??), but the next blue bar (a
trip to Maui) indicates 80 (~28 °C ??). Please clarify?(by the way, there
is an unlabled bar on the extreme left, to the left of the first Hoodsport
trip. Maybe there was a trip to a site where no locality has been
defined??). So it may be that the blue vertical bar indicates the minimum
and the maximum values for a specific trip?? If so, the values for SAC look
realistic if the measurement unit is l/min. The temperatures looks
realistic if the measurement unit is °F. The depth values look realistic if
the measurement unit is m (except that six dive trips have a minimum dive
depth of zero).

Comment 1. For this type of graph, it is critical that the calculations are
done for a *selected set of dives* (i.e. those that have been selected
directly from the dive list or through the filter tool). I see the tab for
"Trips" is highlighted here, meaning the graphs are done for *trips* (i.e.
the leftmost bar indicates a *trip* to Hoodsport). It would be very
valuable to include the number of dives in brackets after the name of the
trip, e.g. the trip to Hoodsport may be indicated as *Hoodsport, WA, USA
(6)*. The six in brackets would indicates that this trip comprised six
dives and that the leftmost bar for Hoodsport summarises six dives.

Comment 2. In a statistics panel is would be proper to indicate the
measurement units (e.g. C or °F for temperature and m/ft for depth and
l/min or ft3/min for SAC.

Comment 3. As Davide has argued, there is no reason to keep the depth
profile while showing statistics, because the depth profile has nothing to
do with the statistics being shown. On the other hand, since the dive list
shows which dives or trips have been selected and the map shows all dives
in an area, one could argue that these panels have some relevance to the
statistics being shown. Admitting that I know nothing of what the Qt/QML
implications may be, there is therefore no reason why the statistics panel
may not be extended to the right to cover the profile panel as well.

Comment 4. For long trip names it is probably useful if only the first
15-20 characters of a trip or dive site name is used, otherwise the
vertical space for creating graphs becomes very small. My own dive
localities have rather long names.

Comment 5. It might enhance the readability of the graphs if, across the
panel, there are horizontal light grey lines that correspond to every 10
units on the vertical axis. This would allow easier interpretation of bars
located towards the right hand side of the panel.

I hope you find this helpful. Thank you for your time and perseverance in
doing this. This is going to be a very nice feature.

Kind regards,
willem
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