Semi Log Scale
Printed From: BullCharts Forum
Category: BullCharts
Forum Name: BullCharts discussion
Forum Discription: General discussion about getting started with BullCharts and exploring its features.
URL: http://www.bullcharts.com.au/forum/forum_posts.asp?TID=500
Printed Date: 12 Apr 2025 at 6:37am
Software Version: Web Wiz Forums 9.69 - http://www.webwizforums.com
Topic: Semi Log Scale
Posted By: Bushy
Subject: Semi Log Scale
Date Posted: 06 Sep 2008 at 11:19pm
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Hi. I was just wondering what people think of semi-log scale vs a normal price scale as the default setting. I have always used a normal scale and am interested in using semi-log but feel a bit out of my comfort zone. What do you all think? |
Replies:
Posted By: rcameron
Date Posted: 15 Sep 2008 at 12:06pm
| Bushy I use a semi log all the time because I feel it gives a better feel for the the % change in price. The normal scale creates distortions because it is automatically scaled and often (for me) I reach different conclusions from the chart when using different scales. Semi log creates consistency and reduces subjectivity, especially if you are looking at charts with a year or two of history or the price has increased rapidly in that time. When trading I want to have a good understanding if things have moved 10% rather than dollar increments and so I can make valid conclusions over time. Semi log suits my trading style but it may not suit yours. Cheers Rod |
Posted By: rbbrain
Date Posted: 25 Nov 2008 at 12:22pm
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hi all,
I agree with Rod an deverything he says there. Test this scenario: look for a chart (stock or index) where the price is increasing at a steeper and steeper angle (eg. XAO index from Jan 2003 to Dec 2007). You can't put a straight trend line under the price action on the linear scaled price axis. But change to semi-log, and VOILA!! a trend line fits snuggly under the price action for the 4+ years of the bull market. - Very Useful
 In Melbourne I know of a few staunch supporters of semi-log charts amongst the ATAA members, and some of our Melbourne BC User Group members.
BTW: Be careful with terminology - some people get confused. The "semi-log" chart is calle dthat because one scale is a logarithmic scale, and one is linear. That is, the price scale is truly logarithmic. Mind you the horizontal price scale is "normally" linear on the line chart and candles and bars (but it isn't on some charts like Renko, Kagi, swing charts, etc., etc.) ------------- Convenor - Australian BullCharts User Group http://www.RobertBrain.com - Brainy's Share Market Toolbox and BullCharts Tips [/CENTER |
Posted By: peter1
Date Posted: 26 Nov 2008 at 7:47pm
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I want to see this exponential curve in a linear chart as it is a great indicator to take profits. If the curve is smoothed out then you will not see this opportunity. Semi log charts are good when viewing long term charts (>5 yr). You may notice that they are also handy after a long move down as the recent price data is "magnified". This makes pattern spotting slightly easier. The many recent key reversals in the ASX look much better using the semi-log scale.
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Posted By: rbbrain
Date Posted: 26 Nov 2008 at 11:10pm
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Hi,
I think it is important for us all to see that different people see different things. I look to switch between them.
eg. have a look at inex XAO from 2002 to 2007 - on semi-log chart it is linear and we can draw one straight trend line under the price action from early 2003 to late 2007. With a linear scale we could not draw one trend line, it would be several. The important point in this example is that the index was continually increasing at the same percentage amount over these 4 years. It would be hard to se this with a linear scale.
But it is important to view both at times.
------------- Convenor - Australian BullCharts User Group http://www.RobertBrain.com - Brainy's Share Market Toolbox and BullCharts Tips [/CENTER |
Posted By: Bana
Date Posted: 13 Feb 2009 at 5:38pm
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I use semi log only. Its matter of personal preference. I used to use a software which did not have semi log so I never I was missing anything. After using bullcharts, I found semilog more suitable visually for my analysis. For a while I tried to view all my candidates in both scales. It became cumbersome process but helped me make decision that I was more comfortable with semi log. Now irrespective of timeframe, I just use semilogs.
I also use semi log on volume bars as it complements the price analysis on same scale.
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