hi,

Im trying to calculate bollinger bands using investbulls historical tick data for last 20 days & std dev=2. but my values don't match at all with yahoo finance/ invest bull charts or other sites.

For bollinger bands, at 9:56am today, I'm using last 20 days close nse data at 9:56 am. why are my calculations different than calculations on these chart websites ?

Thanks in advance.

firstly, are you using the tick data or end-of-day data for calculating the values?

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20 day 9:56am tick close price
eg:
85.8, 86.45, 85.3, 84.5, 83.55, 79.2, 78.55, 82.0, 85.5, 81.0, 82.05, 86.0, 92.0, 95.9, 94.85, 94.8, 96.5, 96.2, 94.1, 96.0

my bbands:
low -> 75.71
mid -> 88.01
high -> 100.31

yahoo & investbulls -> way below

yahoo & investbulls -> 84.5 to 86
even they have std dev =2

What security is this data for?

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this data is for 3iinfotech, but my bollinger bands go wrong for all of them.

I am trying to figure out how charts at these sites work.

I checked charts with EOD data on investbulls.

the charts show the correct value for 20 DMA.

tell me a few things:

how do I change the settings for bollinger bands?
how do I see the 9:56 tick data at investbulls?
why are you working with 9:56 tick data and not the EOD data?

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Thank you for looking into my problem.

Let's say you are looking at an intra-day chart.
Let's focus only on bollinger band value at 9:56am.

My formula =>
Bollinger band for today at 9:56am is calculated using last 20days tick data at 9:56am. ( Historical Tick data obtained from the download url).

1. I feel I cannot use EOD data.
If I use EOD close of last 20 days, my bands will be flat.
HOw else can I use the EOD data for an intraday bollinger bands.

Thanks again.