13 votes

Why does creation of a Q–Q plot in Excel need an adjustment by 0.5?

The missing idea here is often called plotting position, which is a precise recipe for the version of cumulative probability to be used. With your example of $20$ data points, plotting against (...
Nick Cox's user avatar
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7 votes
Accepted

Why does creation of a Q–Q plot in Excel need an adjustment by 0.5?

It is to make the distribution symmetrical. The values 0 to 19 are just as reasonable as the values 1 to 20. If you would have five values you would get quantiles $$0.1,0.3,0.5,0.7,0.9$$ instead of $$...
Sextus Empiricus's user avatar
6 votes

Gaps in a histogram in sampling distribution

It's a bad plot - there should never be space between histogram bars binning continuous data. The plot as shown indicates there were no observations between 0.2 and 0.21 (or in any other gap), which ...
Nuclear Hoagie's user avatar
6 votes

Gaps in a histogram in sampling distribution

At first I thought it was just an aesthetic choice on the part of the chart's creator to add a little padding around bin, in the style of a bar chart. But whuber's comment is insightful: the ...
jdonland's user avatar
  • 227
4 votes

Logarithmic scale use cases

I would recommend on balance against logarithmic scales for bar charts. The best reason for that is that there is a constructive alternative, using logarithmic scales and (Cleveland) dot charts. The ...
Nick Cox's user avatar
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4 votes

Why does creation of a Q–Q plot in Excel need an adjustment by 0.5?

If you have $n$ values sorted in order with indices $i \in \{1,2,\ldots, n\}$ and $n$ is odd, then using a symmetry argument, you presumably want the middle value with index $i=\frac {n+1}2$ to ...
Henry's user avatar
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2 votes
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Gaps in a histogram in sampling distribution

You can adjust the breaks parameter in the hist function to have fewer bins. The first plot (51 bins) might not align perfectly ...
ADAM's user avatar
  • 669
1 vote
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How to interpret the plots of smooths from a GAM object

Answer I'm not sure which text you are referring to, but I think the answer is fairly straightforward. Our $x_1$ here clearly has a consistent positive linear effect on $y$ and has a very narrow ...
Shawn Hemelstrand's user avatar
1 vote

Information from plot of sorted values of a vector

Matthew's answer is sufficient, but I thought somebody should answer the actual question(s) as asked: What would following plot convey? Percentile values: This graph is the graph of percentiles; the ...
agone's user avatar
  • 111

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