Help in understanding the graphs in technical papers

In summary: I have used excel to make bar charts. But even that is a bit of a hack. In summary, when viewing graphs in research papers and journal articles, the little rods with bars on them protruding from the data points are called error bars. They represent the uncertainty of the data points and can be interpreted as "plus-minus" values. There are various software programs available to make these graphs, but Excel is not recommended for scientific work. The main purpose of these graphs is to convey a general idea, rather than provide exact quantities.
  • #1
sk381
19
0
When one sees graphs that are published in research papers and journal
articles, all data points have little rods with bars on them
protruding from them on either side..
What are these for and how does one interpret them?

Thanks
 
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  • #2
Originally posted by sk381
When one sees graphs that are published in research papers and journal
articles, all data points have little rods with bars on them
protruding from them on either side..
What are these for and how does one interpret them?

Thanks

It would help if you cite the papers you see these from. But assuming that I think I know what you are referring to, these "bars" are error bars. They are the "plus-minus" values in the uncertainty of the data points.

Zz.
 
  • #3
Is there any link that you can suggest where I can learn how to make these using excel etc.. and also the theory behind them.. Also since the graphs themselves are so small, are these bars conveying any real information except giving a qualitative feel foe the amount or error.. sort of like the the distance bar in a map..
 
  • #4
Originally posted by sk381
Is there any link that you can suggest where I can learn how to make these using excel etc.. and also the theory behind them.. Also since the graphs themselves are so small, are these bars conveying any real information except giving a qualitative feel foe the amount or error.. sort of like the the distance bar in a map..

The graphs in most physics papers that are published are mainly to convey some messages. They are not meant for one to actually get an exact quantity directly from. Typically, if one is interested in the actual data, one contacts the author/s directly. That is why they are small and only try to convey a general idea only. This is especially true in journals such as Phys. Rev. Lett. that has a page limit of only 4 typeset pages - most authors try to cram as much as they can in those pages resulting in graphs that are sometime small.

I have no idea how to do that using Excel, nor would I recommend using it to make scientific graphs (it isn't meant to do that). If you're in school, there are many graphing software that have special student/educational discounts. Try looking at Kaleidagraph, PsiPlot, Origin (which is what I use), SigmaPlot, etc. However, I think I just made the assumption here that you're in a US educational institution, which may nor may not apply to you.

Zz.
 
  • #5
Excel is designed for business applications, it STINKS for scientific style work. One can nearly create error bars using stock hi lo charting, it is hard and does not work well. Generally you will not see error bars on Excel charts. I make lots of what excel calls scatter charts but even that is weak for real data, because you need to have the same x values for all data series, frequently, this is not how real data is recorded.
 

1. How do I interpret the data presented in a graph?

When looking at a graph in a technical paper, you should first identify the variables on the x and y axes. These represent the factors being measured and how they are related. Then, look at the units of measurement and the scale of the axes to understand the magnitude of the data. Finally, analyze the shape and trend of the graph to draw conclusions about the relationship between the variables.

2. What is the purpose of including a graph in a technical paper?

Graphs are often used in technical papers to visually represent data and trends in a concise and easy-to-understand manner. They can help readers quickly grasp the main points and relationships between variables, making the information more accessible and impactful.

3. What types of graphs are commonly used in technical papers?

The type of graph used in a technical paper depends on the type of data being presented. Some common types include line graphs, bar graphs, scatter plots, and histograms. Line graphs are useful for showing trends over time, while bar graphs are good for comparing different categories. Scatter plots can show the relationship between two variables, and histograms are used to display the distribution of data.

4. How can I determine the accuracy of the data in a graph?

The accuracy of data in a graph can be determined by looking at the source and methodology of the data collection. In scientific research, data is typically gathered through controlled experiments or observations, and the results are analyzed using statistical methods. It is important to also consider the sample size and any potential biases that may affect the data.

5. Is it necessary to include a graph in a technical paper?

No, it is not always necessary to include a graph in a technical paper. However, graphs can be a powerful tool for visualizing complex data and making it more understandable for readers. If the data can be effectively presented and analyzed in a graph, it can enhance the overall clarity and impact of the paper.

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