Uncertainty help needed

[ThemisIsNoMore]

I'm wondering if it's required to take into consideration both the systematic error and the random error in my IA.

Example:

Systematic error 0.03

Measurements:

t1= 0.78

t2= 0.75

t3= 0.77

t4= 0.76

t5= 0.76

So once again - my question is: Do I add the two uncertainties together, or do I simply take into account the random error.

Thanks in advance.

P.S.: I searched for a topic like this and couldn't find it, if it exists already - my apologies.

[CkyBlue]

You should calculate both percentage error and percentage uncertainty in order to do analysis in the C/E part of a lab. Random error and systematic error aren't really calculated, but they are characterized.

Random error is the equal probability of a reading being too high or too low- I guess you can associate that with percentage uncertainty

I don't see any calculation, or uncertainty, and so I don't understand your question when you say "add the uncertainties". Are you trying to find an average value?

Error percentages should be given as a percentage value by the way.

[Drake Glau]

I'm wondering if it's required to take into consideration both the systematic error and the random error in my IA.

Example:

Systematic error 0.03

Measurements:

t1= 0.78

t2= 0.75

t3= 0.77

t4= 0.76

t5= 0.76

So once again - my question is: Do I add the two uncertainties together, or do I simply take into account the random error.

Thanks in advance.

P.S.: I searched for a topic like this and couldn't find it, if it exists already - my apologies.

I'm assuming this example involves a electronic measuring tool of some sorts

Measurements:

t1= 0.78+/-0.003

t2= 0.75+/-0.003

t3= 0.77+/-0.003

t4= 0.76+/-0.003

t5= 0.76+/-0.003

^That's what you get. Random error is addressed in your evaluation for you to discuss the authenticity of your results. Systematic error and normal uncertainty (the rules you learned about absolute uncertainty) should be added. If the machine is really off by 0.003 (like you have an amp meter showing 0.003 but the circuit is broken so it should say 0) you should try to fix it, but otherwise it's just another uncertainty in your measurement. I hope that was what you were looking for

[ThemisIsNoMore]

You should calculate both percentage error and percentage uncertainty in order to do analysis in the C/E part of a lab. Random error and systematic error aren't really calculated, but they are characterized.

Random error is the equal probability of a reading being too high or too low- I guess you can associate that with percentage uncertainty

I don't see any calculation, or uncertainty, and so I don't understand your question when you say "add the uncertainties". Are you trying to find an average value?

Error percentages should be given as a percentage value by the way.

I know that, but let me give you an example.

I have to calculate the speed. And I'm using the measurements written above, and my independent variable is, let's say for the sake of the argument, displacement.

s1=0,5

v max= 0.5/0.75

v min= 0.5/0.78

uncertainty = result of those above / 2

And then of course I transform it into percentages. So my question is, do I add the initial percentage error to this or do I simply leave it as it is?

[ThemisIsNoMore]

I'm wondering if it's required to take into consideration both the systematic error and the random error in my IA.

Example:

Systematic error 0.03

Measurements:

t1= 0.78

t2= 0.75

t3= 0.77

t4= 0.76

t5= 0.76

So once again - my question is: Do I add the two uncertainties together, or do I simply take into account the random error.

Thanks in advance.

P.S.: I searched for a topic like this and couldn't find it, if it exists already - my apologies.

I'm assuming this example involves a electronic measuring tool of some sorts

Measurements:

t1= 0.78+/-0.003

t2= 0.75+/-0.003

t3= 0.77+/-0.003

t4= 0.76+/-0.003

t5= 0.76+/-0.003

^That's what you get. Random error is addressed in your evaluation for you to discuss the authenticity of your results. Systematic error and normal uncertainty (the rules you learned about absolute uncertainty) should be added. If the machine is really off by 0.003 (like you have an amp meter showing 0.003 but the circuit is broken so it should say 0) you should try to fix it, but otherwise it's just another uncertainty in your measurement. I hope that was what you were looking for

It's not 0.003, it's 0.03... That is the whole point. The systematic error is very large, and that can't be helped, because those are seconds.

[ibstudent112]

add them

[CkyBlue]

You should calculate both percentage error and percentage uncertainty in order to do analysis in the C/E part of a lab. Random error and systematic error aren't really calculated, but they are characterized.

Random error is the equal probability of a reading being too high or too low- I guess you can associate that with percentage uncertainty

I don't see any calculation, or uncertainty, and so I don't understand your question when you say "add the uncertainties". Are you trying to find an average value?

Error percentages should be given as a percentage value by the way.

I know that, but let me give you an example.

I have to calculate the speed. And I'm using the measurements written above, and my independent variable is, let's say for the sake of the argument, displacement.

s1=0,5

v max= 0.5/0.75

v min= 0.5/0.78

uncertainty = result of those above / 2

And then of course I transform it into percentages. So my question is, do I add the initial percentage error to this or do I simply leave it as it is?

The uncertainty is the value of the measurement being read too high or too low. If your displacement has an uncertainty, and your velocity has an uncertainty, you must convert them into percentage uncertainties and add the percentages when you divide them.

Wait, I think I recognize what you're doing...

v max=0.67

v min=0.64

So your speed would be reported as 0.655 (0.66 if you don't have the extra decimal places) +/- 0.015

You never add percentage error to the uncertainty. Percentage error is when you compare your experimental value to a literature value.