I used this query to determine the amount of asked and unanswered questions grouped by the hour of asking the question.
This is what the data looks like when plotted with gnuplot:
There percentage of answered questions fluctuates between 57.78% and 62.88%.
From the graph it looks like questions asked between 5 and 7 are less likely to be answered and i'm sure one can find a correlation that explains this(More people asking than people answering questions online?), but i doubt that there is a statistical significance.
Here is another plot of the data, with the amount of questions asked in an hour on the x-axis and the percent of questions answered in an hour on the y axis for the 24 hours of the day.
I also ran a query to determine the average wait time, but i do not see any connection to the time of asking. (This query only measures the time between asking the question and the "accepted" answer being posted, so it also only includes questions with an accepted answer)
I think i also came up with a query to determine the average time it takes for a first answer to be posted (ignoring unanswered questions). But i'm unsure how to interpret it. It looks like you can get a first answer a lot quicker, if you ask it at 4, taking an average of more than 8 days. In comparison to asking at 7, when it takes an average of 12 days for a first answer to be posted.
I'm not an expert on statistics or the stackexchange-data-api so take this with a grain of salt. The data provided might be misleading or not suitable for answering the question at all. Feel free to point out any mistakes.
The script used for plotting:
set datafile separator ","
f = "QueryResults.csv"
set xlabel "Hour of asking"
set ylabel "Questions"
set y2label "Percent Answered"
set ytics nomirror
set xtics (0,2,4,6,8,10,12,14,16,18,20,22,24)
set format y2 '%2.0f%%'
plot f using 1:2 with linesp title "Question Asked", \
f using 1:3 with linesp title "Question Answered", \
f using 1:($4*100) with linesp axis x1y2 title "Percent Answered"
set ylabel "Percent Answered"
set xlabel "Questions Asked"
set format y '%2.0f%%'
set xtics auto
plot f using 2:($4 * 100) with linesp notitle, '' using 2:($4 * 100):1 with labels point pt 7 offset char 0.5,0.5 notitle