UserReference:P300ClassifierMethods - Revision history

Cmpotes: User Reference:Methods moved to UserReference:P300ClassifierMethods: It is most appropriate.

2009-09-14T00:08:25Z

User Reference:Methods moved to UserReference:P300ClassifierMethods: It is most appropriate.

← Older revision		Revision as of 00:08, 14 September 2009
(No difference)

Cmpotes: /* Get P300 Responses */

2009-09-12T21:35:03Z

Get P300 Responses

← Older revision		Revision as of 21:35, 12 September 2009
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	<math>		<math>
	N = round(\frac{Fs}{Df}) = round(\frac{256}{20}) = 13		N = round \left(\frac{Fs}{Df}\right) = round \left(\frac{256}{20}\right) = 13
	</math>		</math>

Cmpotes: /* Get P300 Responses */

2009-09-12T21:33:00Z

Get P300 Responses

← Older revision		Revision as of 21:33, 12 September 2009
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	<math>		<math>
	N = \frac{Fs}{Df}		N = round(\frac{Fs}{Df}) = round(\frac{256}{20}) = 13
	</math>		</math>

Cmpotes: /* Load BCI2000 Data Files */

2009-09-12T21:31:36Z

Load BCI2000 Data Files

← Older revision		Revision as of 21:31, 12 September 2009
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	[[Image:P3SpellerScreen.PNG\|center\|frame\|A 6 by 6 speller matrix. Here, the user's task is to spell the word "SEND" (one character at a time). For each character, all rows and columns in the matrix are intensified 15 times (here, the third row is shown intensified).]]		[[Image:P3SpellerScreen.PNG\|center\|frame\|A 6 by 6 speller matrix. Here, the user's task is to spell the word "SEND" (one character at a time). For each character, all rows and columns in the matrix are intensified 15 times (here, the third row is shown intensified).]]

	Assume that the data set is recorded from 8 channels at 256 Hz, the elapsed time from the start to the end of each intensification is 800 ms, and the ~~decimation frequency~~ provided by the investigator is 20 Hz. For this example, <math> m = 12x15x4 = 720 </math>, <math> l = 8 </math>, and <math> p = round(256 x 0.800) = 205 </math>. The total number of columns (variables) of the above matrix is <math> 8 x 205 = 1640 </math>.		Assume that the data set is recorded from 8 channels at 256 Hz, the elapsed time from the start to the end of each intensification is 800 ms, and the [[User_Reference:P300_classifier#Parameters Pane\|'''Decimation Frequency''']] provided by the investigator is 20 Hz. For this example, <math> m = 12x15x4 = 720 </math>, <math> l = 8 </math>, and <math> p = round(256 x 0.800) = 205 </math>. The total number of columns (variables) of the above matrix is <math> 8 x 205 = 1640 </math>.

	== Get P300 Responses ==		== Get P300 Responses ==

Cmpotes: /* Get P300 Responses */

2009-09-12T21:30:28Z

Get P300 Responses

← Older revision		Revision as of 21:30, 12 September 2009
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	== Get P300 Responses ==		== Get P300 Responses ==

	In this step, it is computed the corresponding time samples of a time [[User_Reference:P300_classifier#Parameters Pane\|'''Response Window''']] <math> [t_{1}, t_{2}] </math> in (ms) specified by the investigator.		In this step, it is computed the corresponding time samples of a time [[User_Reference:P300_classifier#Parameters Pane\|'''Response Window''']] <math> [t_{1}, t_{2}] </math> in (ms). Following the above example, assume that the time Response Window specified by the investigator is [0 800] ms.

	<math>		<math>

Cmpotes: /* Load BCI2000 Data Files */

2009-09-12T21:27:23Z

Load BCI2000 Data Files

← Older revision		Revision as of 21:27, 12 September 2009
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	[[Image:P3SpellerScreen.PNG\|center\|frame\|A 6 by 6 speller matrix. Here, the user's task is to spell the word "SEND" (one character at a time). For each character, all rows and columns in the matrix are intensified 15 times (here, the third row is shown intensified).]]		[[Image:P3SpellerScreen.PNG\|center\|frame\|A 6 by 6 speller matrix. Here, the user's task is to spell the word "SEND" (one character at a time). For each character, all rows and columns in the matrix are intensified 15 times (here, the third row is shown intensified).]]

	~~The~~ data set is recorded from 8 channels at 256 Hz, ~~and~~ the elapsed time from the start to the end of each intensification is 800 ms. For this example, <math> m = 12x15x4 = 720 </math>, <math> l = 8 </math>, and <math> p = round(256 x 0.800) = 205 </math>. The total number of columns (variables) of the above matrix is <math> 8 x 205 = 1640 </math>.		Assume that the data set is recorded from 8 channels at 256 Hz, the elapsed time from the start to the end of each intensification is 800 ms, and the decimation frequency provided by the investigator is 20 Hz. For this example, <math> m = 12x15x4 = 720 </math>, <math> l = 8 </math>, and <math> p = round(256 x 0.800) = 205 </math>. The total number of columns (variables) of the above matrix is <math> 8 x 205 = 1640 </math>.

	== Get P300 Responses ==		== Get P300 Responses ==

Cmpotes: /* Get P300 Responses */

2009-09-12T20:25:28Z

Get P300 Responses

← Older revision		Revision as of 20:25, 12 September 2009
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	Signals of interest are extracted from <math> \mathbf{X_{i}^{k}(n)} </math> and are defined		Signals of interest are extracted from <math> \mathbf{X_{i}^{k}(n)} </math> and are defined
	only for <math> n_{1}\le n ~~\le~~ n_{2} </math>.		only for <math> n_{1}\le n < n_{2} </math>.

	The coefficients <math> b_{i} </math> of the [http://en.wikipedia.org/wiki/Moving_average Moving Average (MA)] filter are found as		The coefficients <math> b_{i} </math> of the [http://en.wikipedia.org/wiki/Moving_average Moving Average (MA)] filter are found as

Cmpotes: /* Load BCI2000 Data Files */

2009-09-12T20:22:28Z

Load BCI2000 Data Files

← Older revision		Revision as of 20:22, 12 September 2009
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	{\mathbf{X_{i}^{k}(n)}} =		{\mathbf{X_{i}^{k}(n)}} =
	\begin{bmatrix}		\begin{bmatrix}
	x_{1}^{1}(1) & x_{1}^{1}(2) & \cdots & x_{1}^{1}(p) & \cdots & x_{1}^{l}(1) & x_{1}^{l}(2) & \cdots & x_{1}^{l}(p) \\		x_{1}^{1}(0) & x_{1}^{1}(1) & \cdots & x_{1}^{1}(p-1) & \cdots & x_{1}^{l}(0) & x_{1}^{l}(1) & \cdots & x_{1}^{l}(p-1) \\
	x_{2}^{1}(1) & x_{2}^{1}(2) & \cdots & x_{2}^{1}(p) & \cdots & x_{2}^{l}(1) & x_{2}^{l}(2) & \cdots & x_{2}^{l}(p) \\		x_{2}^{1}(0) & x_{2}^{1}(1) & \cdots & x_{2}^{1}(p-1) & \cdots & x_{2}^{l}(0) & x_{2}^{l}(1) & \cdots & x_{2}^{l}(p-1) \\
	\vdots & \vdots & \cdots &\vdots & \cdots & \vdots & \vdots & \cdots & \vdots \\		\vdots & \vdots & \cdots &\vdots & \cdots & \vdots & \vdots & \cdots & \vdots \\
	x_{m}^{1}(1) & x_{m}^{1}(2) & \cdots & x_{m}^{1}(p) & \cdots & x_{m}^{l}(1) & x_{m}^{l}(2) & \cdots & x_{m}^{l}(p) \\		x_{m}^{1}(0) & x_{m}^{1}(1) & \cdots & x_{m}^{1}(p-1) & \cdots & x_{m}^{l}(0) & x_{m}^{l}(1) & \cdots & x_{m}^{l}(p-1) \\
	\end{bmatrix}		\end{bmatrix}
	</math>		</math>
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	<math> k = 1, 2, \ldots, l; </math>		<math> k = 1, 2, \ldots, l; </math>

	<math> n = 1~~, 2~~, \ldots, p; </math>		<math> n = 0, 1, \ldots, p-1; </math>

	being <math> m </math> the total number of observations (stimuli), <math> l </math> the total number of channels, and <math> p = t*Fs </math> the total number of samples recorded for each channel. <math> t </math> is the recording stimulus time, and <math> Fs </math> is the sampling frequency.		being <math> m </math> the total number of observations (stimuli), <math> l </math> the total number of channels, and <math> p = t*Fs </math> the total number of samples recorded for each channel. <math> t </math> is the recording stimulus time, and <math> Fs </math> is the sampling frequency.

Cmpotes: /* Get P300 Responses */

2009-09-12T20:17:42Z

Get P300 Responses

← Older revision		Revision as of 20:17, 12 September 2009
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	<math>		<math>
	n_{1} = round\left(\frac{t_{1}Fs}{1000}\right)		n_{1} = round\left(\frac{t_{1}Fs}{1000}\right) = round\left(\frac{0*256}{1000}\right) = 0
	</math>		</math>

	<math>		<math>
	n_{2} = round\left(\frac{t_{2}Fs}{1000}\right)		n_{2} = round\left(\frac{t_{2}Fs}{1000}\right) = round\left(\frac{800*256}{1000}\right) = 205
	</math>		</math>

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	The output <math> y_{i}^{k}(n)</math>, result of the convolution between all the extracted signals —for channels <math> k = 1, 2, \ldots, l </math> and observations <math> i = 1, 2, \ldots, m </math>— and the impulse response, is [http://en.wikipedia.org/wiki/Downsampling downsampled] by a factor <math> N </math>.		The output <math> y_{i}^{k}(n)</math>, result of the convolution between all the extracted signals —for channels <math> k = 1, 2, \ldots, l </math> and observations <math> i = 1, 2, \ldots, m </math>— and the impulse response, is [http://en.wikipedia.org/wiki/Downsampling downsampled] by a factor <math> N </math>.


	== Generate Feature Weights for a Linear Model using Stepwise Linear Discriminant Analysis (SWLDA) ==		== Generate Feature Weights for a Linear Model using Stepwise Linear Discriminant Analysis (SWLDA) ==

Cmpotes: /* Load BCI2000 Data Files */

2009-09-12T20:12:12Z

Load BCI2000 Data Files

← Older revision		Revision as of 20:12, 12 September 2009
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	[[Image:P3SpellerScreen.PNG\|center\|frame\|A 6 by 6 speller matrix. Here, the user's task is to spell the word "SEND" (one character at a time). For each character, all rows and columns in the matrix are intensified 15 times (here, the third row is shown intensified).]]		[[Image:P3SpellerScreen.PNG\|center\|frame\|A 6 by 6 speller matrix. Here, the user's task is to spell the word "SEND" (one character at a time). For each character, all rows and columns in the matrix are intensified 15 times (here, the third row is shown intensified).]]

	The data set is recorded from 8 channels at 256 Hz, and the elapsed time from the start to the end of each intensification is 800 ms. For this example, <math> m = 12x15x4 = 720 </math>, <math> l = 8 </math>, and <math> p = round(256 x 0.800) = 205 </math>. The total number of columns of the above matrix is <math> 8 x ~~256~~ = ~~2048~~ </math>.		The data set is recorded from 8 channels at 256 Hz, and the elapsed time from the start to the end of each intensification is 800 ms. For this example, <math> m = 12x15x4 = 720 </math>, <math> l = 8 </math>, and <math> p = round(256 x 0.800) = 205 </math>. The total number of columns (variables) of the above matrix is <math> 8 x 205 = 1640 </math>.

	== Get P300 Responses ==		== Get P300 Responses ==