Calculation of rise time of skin conductance data

Hello Matlab experts,

To calculate the rise time of Skin Conductance Response, I used the risetime (x) function in Matlab but it does not calculate the risetime correctly. Could you please help me how to solve this. My supervisor suggested me to calculate the derivative of the signal (which takes the peak velocity of the signal) and I do not know how to do so.

I have attached the data.

Dataset expalanation:

There is one observation point per second in each column- Starts from 0 time to 25 s post stimulus, the risetime happens between 1 to 3 s and the rise time length is between 1 to 3s itself.

I need a simple code (with the loop function) that calculates the derivatie of each row of data and save the derivates of all rows.

Your help is highly appreciated,

Thank you very much,

Answer 1

[Star Strider]

The data are certainly available, however making sense out of them is difficult.

Is there a time vector?

The risetime function will not work here, because this is not a bilevel waveform. It is necessary to interpolate to get the appropriate values.

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/778048/SCR.xlsx', 'VariableNamingRule','preserve')

T1 = 1775×27 table
    ParticipantID      Zero          One          Two         Three        Four        Five        Six        Seven       Eight        Nine        Ten        Eleven      Twelve     Thirteen    Fourteen    Fifteen     Sixteen     Seventeen    Eighteen    Nineteen     Twenty     twentyone    Twentytwo    Twentythree    Twentyfour    Twentyfive
    _____________    _________    _________    __________    ________    ________    ________    ________    ________    ________    ________    ________    ________    ________    ________    ________    ________    ________    _________    ________    ________    ________    _________    _________    ___________    __________    __________

    {'i6ef19xt'}      -0.00013     0.000318      0.000669    0.001844    0.001876    0.001696    0.001535    0.001718    0.001178    0.000972    0.001491    0.001445     0.00117    0.001285    0.001191    0.001049    0.001212    0.000853     0.000766    0.000928    0.000666    0.000855     0.000867      0.000529       0.000426     0.00049359
    {'i6ef19xt'}      0.000157      0.00034      0.000514    0.004069    0.003753    0.004665    0.004652    0.004124    0.003611    0.002678    0.002146    0.002194    0.001275    0.001092    0.004428    0.006963    0.007007    0.006311     0.005216    0.003792    0.001675    0.000838     0.000453      0.000313       0.000262     0.00029941
    {'i6ef19xt'}     -0.000415     -0.00054     -0.000458    0.000312    0.000347    0.000196    0.000246    0.000469    0.000447    0.000284     0.00028     0.00048    0.000485    0.000745    0.000749     0.00095    0.001249    0.001195     0.000672    0.001155    0.004676    0.004088     0.003481      0.002439       0.001515     0.00065515
    {'i6ef19xt'}     -0.000837    -0.000269     -0.000598    0.002262    0.004064    0.005268    0.004625    0.003763    0.003337    0.002087    0.001594    0.001931    0.001983    0.001353     0.00086    0.000745    0.000369     6.4e-05      0.00037    0.000615    0.004278    0.003333     0.003501       0.00334       0.002924      0.0019433
    {'i6ef19xt'}     -0.000262    -0.000653      -0.00053    0.000954    0.000954    0.000554    0.000626    0.001055    0.001353    0.001328    0.001205    0.001879    0.001227    0.000774    0.000629    0.000873    0.001162    0.000811     0.000691    0.000762     0.00277    0.003144     0.003223      0.003377         0.0037      0.0035897
    {'i6ef19xt'}     -0.000106    -0.000663     -0.000158    0.001541    0.001325     0.00103     0.00151     0.00172    0.002208    0.002072    0.001351    0.000934    0.001703    0.001564    0.001978    0.002372    0.002317    0.002259     0.001635    0.001393    0.003659    0.003666     0.003394       0.00267       0.001328      0.0010741
    {'i6ef19xt'}      -7.6e-05      0.00022     -0.000198    0.000772    0.000827     0.00054    0.000901     0.00202    0.001353    0.000641    0.000566     0.00047    0.000509    0.000772    0.000894    0.000928    0.000811    0.000802     0.000669    0.000724    0.002013    0.001861     0.002052       0.00105       0.001736      0.0041724
    {'i6ef19xt'}     -0.000321     -3.2e-05     -0.000632    0.004844    0.016699    0.017774    0.015493     0.01328    0.011465    0.009262    0.007351    0.005364    0.003806    0.002898    0.001611    0.000769     0.00089    0.001225      0.00194    0.002552    0.000701    0.001303      0.00174       0.00205       0.002117      0.0017208
    {'i6ef19xt'}      0.000212    -0.000139      -8.8e-05    0.002591    0.001551    0.000831    0.000587    0.000727    0.003241     0.00515    0.005416    0.004814    0.003785    0.003133    0.002448     0.00274    0.004133    0.004453     0.004379     0.00455    0.001176    0.000786     0.001033      0.000972       0.001261      0.0023003
    {'i6ef19xt'}     -0.000468     -0.00095    -0.0003622     0.00212     0.00248     0.00312    0.004759    0.006155    0.006803    0.008193    0.008944    0.009351    0.010213    0.010311    0.009923    0.009008    0.008055     0.00782     0.007436    0.006797    0.006036    0.005273     0.006113      0.006052       0.005516      0.0050616
    {'i6ef19xt'}         1e-06        8e-05      0.000233     0.00093    0.000804    0.000881    0.000811     0.00043    0.000767    0.000838    0.000607    0.000719    0.000761    0.000869    0.001042    0.000699    0.000697    0.000959     0.000714    0.000486    0.001089    0.001172     0.001399      0.001578       0.001669      0.0015821
    {'i6ef19xt'}      -0.00031    -0.000256      -7.5e-05    0.000568     0.00074    0.000834    0.001041    0.001059    0.000785    0.000683    0.001037    0.000906    0.000551    0.000819    0.001158    0.001051    0.000864    0.000874        0.001    0.000777    0.001936    0.001771     0.001469      0.001452       0.001156      0.0010073
    {'i6ef19xt'}         1e-05        2e-05      0.000968    0.006066    0.005558    0.005162    0.003542     0.00299    0.002557    0.002485    0.002231    0.001959    0.002487    0.003447    0.003486    0.003661    0.003897    0.002536     0.001103    0.001192    0.002534     0.00309     0.003647      0.004369       0.005119      0.0056723
    {'i6ef19xt'}     -0.000337    -0.000717     -0.000424    0.001943    0.001693    0.001908    0.002239    0.002444    0.002555    0.002087    0.001602    0.001717    0.001353    0.001493    0.002009    0.002727     0.00351    0.003458     0.003822    0.004713    0.002391     0.00359     0.003725      0.003138        0.00277      0.0029082
    {'i6ef19xt'}     -0.000915    -0.000747     -0.000309    0.001137    0.001069    0.001364    0.001607    0.002066    0.002133     0.00145    0.001118     0.00111    0.000756    0.000144    0.001264    0.002884    0.003748    0.003054     0.001735    0.001195    0.006026    0.003559     0.002032      0.001143        0.00069     0.00045339
    {'i6ef19xt'}         9e-06     0.000349      0.000507     0.00113    0.000723    0.000582    0.000601     0.00057    0.000507    0.000465    0.000472    0.000718    0.000444    0.000486    0.000464    0.000456    0.000221    0.000558     0.000605     0.00029    0.000451    0.000202      0.00038       0.00065       0.000377     0.00048936

figure
plot(T1{:,2})
grid
title('First Column')

tv = linspace(0, 1, numel(T1{1,2:end}));                                % Create Time Vector
[maxval,maxidx] = max(T1{1,2:end});                                     % First Peak & Index
rise = (T1{1,maxidx}-T1{1,2})*[0.1 0.9];                                % Rise Levels
RefLvls = interp1(T1{1,2:maxidx}, tv(1:maxidx-1), rise);                % Associated Time

figure
plot(tv, T1{1,2:end})
hold on
plot(RefLvls, rise,'+r')
plot(([1;1]*RefLvls), ([1;1]*ylim)', '--r')
hold off
grid
xlabel('Time')
ylabel('Amplitude')
title('First Row')
text(mean(RefLvls),mean(ylim), sprintf('Rise Time = %.5f',diff(RefLvls)), 'Horiz','center', 'Vert','middle', 'Rotation',90)

This should be an appropriate start. Define the appropriate time vector first.

.

[Vida Greyson]

Fantastic community! Thank you very much for your time.

[Star Strider]

As always, my pleasure!

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