Doubt: Missing baseline and manipulated Y-axis

[Gnani Rengachari]

Please explain what is Missing baseline and manipulated Y-axis  

[SUHANA PARVEEN S]

Missing Baseline means in a Bar chart we haven't given Y axis starting from 0. ( for example plz see the attachment below). It's also called Truncated y-axis.

Manipulated Y axis means breaking of Y-axis. When we have to show a large no of variables in Y axis we have break Y axis using Zig zig line. For example, 

we have given a data as

Sana - 3 years

Swapna- 15 years

Mahima-17 years.

Fathima-19 years

Nirmal-22 years

upto a Vinod- 25 years..

when graphing it (X axis belongs to Names & Y axis belong to age )we have seen that it becomes a huge graph.. For making it easier.. Using a zigzag line e in the graph b/w  4-14 which shows there is a break in it..!! ( Please see the attachment below for another example)

Hope this clear!!...

Regards

[Anand Iyer]

Here's what I gathered about variations of manipulated axis and issues due to it.  In fact, I'm also looking and by no means an expert at this:)

All these are from various places on the web.

Manipulation of Y-axis (X-axis can also be manipulated similarly) can happen, either because: 

1.  The axis has been scaled inappropriately.  Thus, instead of displaying a 100 percent units in the Y-axis, you scale up every unit by 2, and thus have 200 units the axis.  This magnifies the error, and hence manipulative.

2.  The axis is either extended or reduced abruptly.  Instead of showing the 100 percent units in the Y-axis, you show only 50; visually conveying something very different from reality.  Hence manipulative.  Note that this different from truncating.

3.  The axis has missing ticks.  Omitting certain percentage points in Y-axis will lead to some missing data points, and this could skew the representation.  This will be especially true if you were using line charts.

4.  Misleading graph with no scale.  This will totally misrepresent and is often used in media.

Attached some pictures I collected from the web.

[Anand Iyer]

Thanks Ram for the encouragement!

On Sat, Oct 17, 2020 at 10:46 AM Ram Devineni <devinen...@gmail.com> wrote:

Hello, Anand,

It's a very good and detailed explanation. 

Best,

Ram,

Statistics-1 Course Support

--

Cheers,

Anand

[Statistics 1 Support 1]

Hello, Anand,

It's a very good and detailed explanation. 

Best,

Ram,

Statistics-1 Course Support

On Saturday, October 17, 2020 at 7:55:24 AM UTC+5:30 anandd...@gmail.com wrote:

[Gnani Rengachari]

Thank you everyone for your time and effort to solve my doubt.

[Malabika Guha Mustafi]

Hello Anand, very  nice explanations .