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How to Draw a Scientific Graph: A Step-by-Step Guide

Updated on June 10, 2016

A very poor, but not unique, example of a graph

This graph is (intentionally) riddled with problems that are commonly seen in student's work. Find out how to avoid these costly mistakes below.
This graph is (intentionally) riddled with problems that are commonly seen in student's work. Find out how to avoid these costly mistakes below. | Source

Graphs - learn to love them!

I hear this moan more than any other - it also is one of the most exasperating:

"Why do we have to draw graphs in Science - it's not maths!"

With Ofsted going on about 'integrated curricula' it is important that students do not see subjects as insular and cut off from each other. The skills learnt in Math, English and Technology are readily and necessarily transferable to the Scientific arena.

Graphs are one of the most important tools available to scientists (young and old) to display data. They are:

  1. Easy to interpret
  2. Display a large amount of information in a small (ish) space
  3. Easy to draw!
  4. Worth LOADS of marks in coursework and in exams (typically 4-8marks)

It is a source of endless annoyance seeing a pupil miss a grade boundary by a couple of marks only to scrutinise the paper and see 3 marks thrown away due to poor graphing. This article will take you through the golden rules of drawing graphs, applicable to all exam boards, all situations, all the time. They are even up on my classroom wall as my 'Tips for the Top'

Common Mistakes, and how to avoid them

At least half the marks for any graph question are awarded for presenting your graph according to standard conventions; this is before the actual content has even been assessed. Before moving on from any graph question or from a graph section of your coursework, ensure you have followed the 6 Graph Commandments

  1. Thou shalt draw your graph in pencil with a ruler.
  2. Thou shalt use all thy graph paper.
  3. Thou shalt label your axes.
  4. Thou shalt always give units.
  5. Thou shalt not draw bar graphs.
  6. Thou shalt not play dot-to-dot with thy data points!

Taking a closer look at that graph - this person has broken five of the six commandments. Even if all their data points are correctly plotted, they have already thrown away half the marks!
Taking a closer look at that graph - this person has broken five of the six commandments. Even if all their data points are correctly plotted, they have already thrown away half the marks!

Be Specific

If you have ticked off each of the Commandments, you are halfway to achieving a good overall mark for this particular graph. But now it is time to pick up question specific marks...

  1. Give your graph a descriptive title. E.g.: A Graph to show the effect of x on y
  2. Ensure you have put your graph the right way around. Your x axis should always show the independent variable - this is the variable you are changing. Your y axis should always plot the dependent variable - this is the variable you are measuring. For example, when looking at the effect of temperature on rate of reaction (a classic chemistry investigation), you change the temperature and measure the rate. As such, temperature goes on your x axis (it is independent) and rate goes on your y axis (it is dependent)
  3. Ensure you plot your data carefully, along the corridor and up the stairs. Mark your data point with a small x. If you are plotting multiple data sets on one graph (a prerequisite for the highest marks in some syllabi) then use a small o or l or similar to distiguish between data sets.
  4. If plotting multiple data sets, WRITE OUT A KEY/LEGEND!
  5. Do not play dot-to-dot. I know I have stated this before, but I so often see jagged connected lines on graphs from my students. Only very rarely are data points connected in this way. More often, we are seeking the trend or pattern that our results show, for that we need...
  6. DRAW A LINE OF BEST FIT. These lines pass through or near as many data points as possible. They can either be straight lined, or a smooth curve. Look for the pattern to decide which is most appropriate.
  7. TIP FOR THE TOP: circle your anomalous results (any outliers that do not fit your trend) and label them in your key/legend. This will net you extra points for seconds extra work.

A near-perfect graph! Following all of the commandments and many of the higher tier specs too. Beautiful.
A near-perfect graph! Following all of the commandments and many of the higher tier specs too. Beautiful. | Source

Don't forget to ask

Depending on the coursework you are completing, the criteria for accessing the very top marks differ. For rates of reaction, you are required to find the gradient of your graph; For osmosis and other biological investigations you are required to add error bars; still other investigations require statistical interventions such as Chi-Squared tests. Graphs are such easy places to pick up precious points that it would be foolish to not ask your teacher/lecturer/professor etc what the marking criteria are for the highest echelons. Don't waste marks by not asking - by following all the above advice, you have already attained 6/8 marks: now shoot for the last two!

Happy Graphing!

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    • TFScientist profile image
      Author

      Rhys Baker 5 years ago from Peterborough, UK

      This is my first hub so please comment! Any improvements, suggestions or criticisms are gratefully received.

    • Ms Dee profile image

      Deidre Shelden 5 years ago from Texas, USA

      What a GREAT first hub! I'm impressed. I've not seen an article about this before. What is the reason behind the 5th commandment? I'm curious. A good title is so very important and you seem to have a good one here :). If it were me, I would not put any more links in than you already have. You have not gone overboard on the tags, either. So, great job!

    • rjsadowski profile image

      rjsadowski 5 years ago

      A very useful hub. People don't graph data enough, probably because they don't know how. Remember the words of that great philosopher, Hugh Heffner, "One picture is worth a thousand words".

    • FitnezzJim profile image

      FitnezzJim 5 years ago from Fredericksburg, Virginia

      My goodness, I use graphs all the time to quickly and intuitively convey messages. Unfortunately, I suppose I no longer follow the rules, although I was taught all those rules when I was growing up.

      Nowadays, a good graph can be done in Excel (so out goes the paper and pencil rules). I try to label the plots and axes, but truth to say, I almost always get comments to make them more readable (bad habit ... when you know what you plotted, and are expecting to tell the story when you are sharing the graph, then the verbal part is usually when the axes get labelled for the viewer. It's part of a technique to engage the audience while presenting). So the units and labelling rules are often broken. Bar graphs have their place, but not for the plots I make. The connect the dots rule usually does not get broken since the data is about as random as the stock market, with both the independent and dependent variables showing randomness. Those sort of graphs look like scribbles if you connect the dots.

      Great Hub, and excellent point that graphs are just another of the many tools a good mathematics person can draw on to help convey messages obscured in data.

      Welcome to Hub Pages.

    • TFScientist profile image
      Author

      Rhys Baker 5 years ago from Peterborough, UK

      Many of my pupils come to secondary school with a good idea of how to draw bar graphs...and nothing else. As such, they plot bar graphs at all times (talk about annoying!) Hence my 5th commandment. Bar graphs are only suitable when graphing the results of a tally chart (categories vs frequency) and are used extremely infrequently about Yr7 in Science.

      @FitnezzJim - I agree RE graphing on PCs (although Excel and Minitab are still very poor at drawing lines of best fit) has now become a norm - for good or ill. However, until all exams and coursework are submitted by PC, the more 'primitive' methods are still relevent...and you would be gobsmacked how many pupils submit graphs drawn on lined or plain paper, in pen, without a ruler. GRRR! :)

      Thank you for the kind words so far. I'm glad I am making myself useful.

    • TFScientist profile image
      Author

      Rhys Baker 5 years ago from Peterborough, UK

      @Ms Dee - huge thanks for your specific comments - really helpful. I will try to keep this as a standard for my hubs

      @rjsadowski: Couldn't agree more

    • bloggernotjogger profile image

      bloggernotjogger 5 years ago from La Cala de Mijas, Spain

      Nice hub,

      I voted up because the hub explained everything the title said it would. The links at the top are great too. I have more material to read.

    • TFScientist profile image
      Author

      Rhys Baker 5 years ago from Peterborough, UK

      Thanks for your kind words :)

    • Teresa Coppens profile image

      Teresa Coppens 4 years ago from Ontario, Canada

      I was just teaching the importance of proper graph construction to a grade 4 class, they were working primarily with bar graphs however but the principle remains the same. Fantastic resource.

    • freemarketingnow profile image

      freemarketingnow 4 years ago from California

      I'm not sure why I can't draw bar graphs. I'm also not sure why there's no title to your graphs. Otherwise, this looks good for someone in elementary school or junior high. Good work for a first hub!

    • TFScientist profile image
      Author

      Rhys Baker 4 years ago from Peterborough, UK

      "I'm also not sure why there's no title to your graphs"

      For my first and third graphs there are titles :S The second graph deliberately doesn't have one. Thanks for the comment. You would be surprised how often degree level students forget the basics!

    • TM 3 years ago

      all teachers keep explaining this to me but i never get it,i just got it now!thanks!

    • tine 24 months ago

      Yeah but how you draw it?

    • christian eneojo 23 months ago

      impressive information...

    • helpmewithschool 17 months ago

      ive been freaking out over a test tomorrow and couldnt find some of these answers anywhere so thank you so much im incredibly grateful. you made me so happy i decided to get an account here just so i could comment on this and thank you. please keep making really great hubs

    • Luize 12 months ago

      Commandment number 2 should be: Thou shalt give your graph a heading!

      Well done. I'm busy with an extensive handout for my kids and was looking for examples of line graphs when I stumbled upon your page. This is well summarized - good job!

    • Marcus 2 months ago

      Thanks so much have an exam tommorow and had failed previously on graphing so thanks for this should hopefully help me improve

    • D Hardy 2 months ago

      According to AQA Biology all points should be joined by straight lines

    • messy 6 weeks ago

      I'm going to okido. this will help me a lot over there

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