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IA help! questions about graphs and terminology


Alicia598

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I'm doing a lab, and my data is very messed up. Unfortunately, I don't think I'm allowed to share the actual graphs on here. So I'll just ask some questions:

 

1. If I'm looking at only two data points, can I say they have a direct relationship? Or would it be safer to say 'positive correlation'?

2. As for a linear graph with a negative gradient - not an inversely proportional relationship, but is it still an inverse relationship?

3. If the data points have significantly large error bars, to the point not being to plot a maximum line, is it fine to just refer to the minimum value? (There is a justified reason why the error bars are large).

 

And yes, I've went to see my teacher about the lab, he was quite vague (understandably I guess), but told me not to redo my experiment...

 

Thanks to anyone with answers....

 

 

 

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1. Two data points is not enough to make a safe conclusion about a relationship. To be absolutely blunt, you can't even say the correlation is positive. The relationship could be periodic, making the graph behave in a wave; it could also be polynomial to a higher degree, so there could be turning points.

 

If you're just strictly talking about the two data points, then yeah I guess you could say they have a positive correlation, but that doesn't give you any information about the relationship between the dependent and independent variables.

 

2. Yeah it would be an inverse relationship. I believe that just means that as one variable goes up, the other goes down. Proportionality just means the variables are bound by a factor of a constant; e.g. y=-2x is an inversely proportional relationship.  But if you have something like y=e^(-x), that would be an inverse relationship.

 

3. Haven't really encountered this before, but I would at least try to graph the points electronically and make note of the maximum slope, just to stick to standard procedure as much as possible. I don't know the nature of your experiment so I can't really say anything about that, but if you have a justified reason then make sure you get your point through in the discussion section of your lab. 

 

Hope this helps :lol:

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