Stuck on IB question that needs GDC for sinusoidal

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Nina Merchant

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Apr 11, 2021, 5:34:10 AMApr 11
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If someone could help me with this using the nspire I would be extremely grateful. many thanks in advance

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Rory Daulton

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Apr 11, 2021, 5:51:29 AMApr 11
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That question has many parts. Which part is giving you difficulty? What is a GDC (Graphing Calculator, perhaps)? If you want us to help you with part c, what part of setting up and executing a sinusoidal regression do you not understand?

hastern

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Apr 11, 2021, 9:46:14 AMApr 11
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Is that an actual IB question? It looks more like a textbook question, in that the setup requires an inordinate amount of time.
The hint to use Hours Post Midnight is good, but leaves an artifact for the switch to and from Summer Time in March and November. I might massage that data to get rid of that bump. Or else pull data relative to UCT / GMT.
The Nspire (Graphic Display Calculator, or GDC) doesn't automatically know what the appropriate period is for this data set. I had to tell the wizard that my period is 364. I didn't try in 84 Plus, but suspect the same issue would arise.
04-11-2021 Image001.jpg

eagl...@duetsoftware.ca

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Apr 11, 2021, 10:48:23 AMApr 11
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Shouldn’t the period be 365 since it starts on day 1 and ends on day 365? (Day 0=day 365)?

On Apr 11, 2021, at 6:46 AM, hastern <has...@gmail.com> wrote:

Is that an actual IB question? It looks more like a textbook question, in that the setup requires an inordinate amount of time.
The hint to use Hours Post Midnight is good, but leaves an artifact for the switch to and from Summer Time in March and November. I might massage that data to get rid of that bump. Or else pull data relative to UCT / GMT.
The Nspire (Graphic Display Calculator, or GDC) doesn't automatically know what the appropriate period is for this data set. I had to tell the wizard that my period is 364. I didn't try in 84 Plus, but suspect the same issue would arise.
<04-11-2021 Image001.jpg>



On Sunday, April 11, 2021 at 11:51:29 AM UTC+2 roryd...@gmail.com wrote:
That question has many parts. Which part is giving you difficulty? What is a GDC (Graphing Calculator, perhaps)? If you want us to help you with part c, what part of setting up and executing a sinusoidal regression do you not understand?

On Sunday, April 11, 2021 at 5:34:10 AM UTC-4 Nina Merchant wrote:
If someone could help me with this using the nspire I would be extremely grateful. many thanks in advance

Captureib.PNG

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John Hanna

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Apr 11, 2021, 11:40:42 AMApr 11
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Any initial period should be good enough for SinReg to work.

 

 

Be Excellent,

     John Hanna

 

From: tins...@googlegroups.com <tins...@googlegroups.com> On Behalf Of eagl...@duetsoftware.ca
Sent: Sunday, April 11, 2021 10:48 AM
To: tins...@googlegroups.com
Subject: Re: [tinspire] Re: Stuck on IB question that needs GDC for sinusoidal

 

Shouldn’t the period be 365 since it starts on day 1 and ends on day 365? (Day 0=day 365)?



On Apr 11, 2021, at 6:46 AM, hastern <has...@gmail.com> wrote:

Is that an actual IB question? It looks more like a textbook question, in that the setup requires an inordinate amount of time.

The hint to use Hours Post Midnight is good, but leaves an artifact for the switch to and from Summer Time in March and November. I might massage that data to get rid of that bump. Or else pull data relative to UCT / GMT.

The Nspire (Graphic Display Calculator, or GDC) doesn't automatically know what the appropriate period is for this data set. I had to tell the wizard that my period is 364. I didn't try in 84 Plus, but suspect the same issue would arise.

<04-11-2021 Image001.jpg>

 

 

On Sunday, April 11, 2021 at 11:51:29 AM UTC+2 roryd...@gmail.com wrote:

That question has many parts. Which part is giving you difficulty? What is a GDC (Graphing Calculator, perhaps)? If you want us to help you with part c, what part of setting up and executing a sinusoidal regression do you not understand?

On Sunday, April 11, 2021 at 5:34:10 AM UTC-4 Nina Merchant wrote:

If someone could help me with this using the nspire I would be extremely grateful. many thanks in advance

 

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<04-11-2021 Image001.jpg>

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hastern

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Apr 12, 2021, 1:58:52 AMApr 12
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When I tried it without the period (which the wizard says is optional) it didn't give me a good model.

John Hanna

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Apr 12, 2021, 6:55:33 AMApr 12
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Any initial period is better than none at all 😉

 

 

Be Excellent,

     John Hanna

Karlheinz Haas

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Apr 12, 2021, 4:26:34 PMApr 12
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I took Howard's idea and adjusted the values from March 26 on until Oct. 22 for DST and even added about 8 weeks to start a new cycle, assuming the sunrise times will be pretty close a year later and got the following scatter plot. And the resulting sinusoidal regression give a pretty good estimate for the sunrise on Feb. 2 (Day 33).

Screen Shot 2021-04-12 at 4.22.14 PM.png

Karlheinz

John Hanna

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Apr 12, 2021, 6:18:02 PMApr 12
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And a residuals plot?

 

 

Be Excellent,

     John Hanna

 

From: tins...@googlegroups.com <tins...@googlegroups.com> On Behalf Of Karlheinz Haas
Sent: Monday, April 12, 2021 4:27 PM
To: tinspire <tins...@googlegroups.com>
Subject: Re: [tinspire] Re: Stuck on IB question that needs GDC for sinusoidal

 

I took Howard's idea and adjusted the values from March 26 on until Oct. 22 for DST and even added about 8 weeks to start a new cycle, assuming the sunrise times will be pretty close a year later and got the following scatter plot. And the resulting sinusoidal regression give a pretty good estimate for the sunrise on Feb. 2 (Day 33).

 

image001.png

Karlheinz Haas

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Apr 12, 2021, 7:02:51 PMApr 12
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You asked...........

Screen Shot 2021-04-12 at 6.59.31 PM.png

John Hanna

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Apr 12, 2021, 8:25:57 PMApr 12
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Thought so!

 

 

Be Excellent,

     John Hanna

 

From: tins...@googlegroups.com <tins...@googlegroups.com> On Behalf Of Karlheinz Haas
Sent: Monday, April 12, 2021 7:03 PM
To: tinspire <tins...@googlegroups.com>
Subject: Re: [tinspire] Re: Stuck on IB question that needs GDC for sinusoidal

 

You asked...........

 

image001.png
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