Having real problems with working out scales for graphs

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In summary, the AS level student doesn't know how to use the scales on their graphs and is wondering if they are doing it wrong. The guidelines provided suggest that scales should occupy at least half the graph grid in both the x and y directions and should be labeled with the quantity plotted. The student finds it difficult to determine the scale since the largest value is smaller than the smallest value and there are only 20 squares in the sequence. They round the scale up to the next number in the sequence which gives a scale of 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135.
  • #1
ThatOneMidget
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I have no clue what I'm supposed to do with the scales for my graphs. I am an AS level student and in the practical paper we're asked to draw a graph using our readings. The marking scheme has this to say:
Axes Scales must be such that the plotted points occupy at least half the graph grid in both the x and y directions (i.e. 4 x 6 in portrait or 6 x 4 in landscape) Axes must be labelled with the quantity plotted. Ignore units. Do not allow awkward scales or gaps of more than three large squares between the scale markings
I have no idea what they mean by awkward scales and what not, what i usually do to decide the scale is (largest value - smallest value)/(number of squares), is that wrong?
 
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  • #2
ThatOneMidget said:
have no idea what they mean by awkward scales
To me it means a scale that doesn't include powers of 10. I generally use scales in which the units are multiples of 1, 2 or 5:

1, 2, 3, 4, 5, ...
2, 4, 6, 8, 10, ...
5, 10, 15, 20, 25, ...
10, 20, 30, 40, 50, ...
20, 40, 60, 80, 100, ...

I would not use scales like

3, 6, 9, 12, 15, ...
7, 14, 21, 28, 35, ...
2.3, 4.6, 6.9, 9.1, 11.4, ...

which would never include 10 or 100 or 1000, etc.

I would take the result of your formula and round it upward to the next number in the following sequence: 1, 2, 5, 10, 20, 50, 100, ...

So if you have smallest = 130.2, smallest = 46.3, number of squares = 20, then your formula gives 4.195, which I would round up to 5. This gives a scale of

45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135

which actually requires only 18 squares to accommodate your data, so I might add one square at the beginning and at the end, with the scale running from 40 to 140.
 
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  • #3
jtbell said:
To me it means a scale that doesn't include powers of 10. I generally use scales in which the units are multiples of 1, 2 or 5:

1, 2, 3, 4, 5, ...
2, 4, 6, 8, 10, ...
5, 10, 15, 20, 25, ...
10, 20, 30, 40, 50, ...
20, 40, 60, 80, 100, ...

I would not use scales like

3, 6, 9, 12, 15, ...
7, 14, 21, 28, 35, ...
2.3, 4.6, 6.9, 9.1, 11.4, ...

which would never include 10 or 100 or 1000, etc.

I would take the result of your formula and round it upward to the next number in the following sequence: 1, 2, 5, 10, 20, 50, 100, ...

So if you have smallest = 130.2, smallest = 46.3, number of squares = 20, then your formula gives 4.195, which I would round up to 5. This gives a scale of

45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135

which actually requires only 18 squares to accommodate your data, so I might add one square at the beginning and at the end, with the scale running from 40 to 140.
Thank you so much!
 
  • #4
JTBell has given the specifics.
But what I would say is, don't look on these as arbitrary rules. Think about why they suggest these "rules".
Apart from general shape, which might be apparent even without scale markings (so long as the nature of the scale was indicated), one often wants to take readings from the graph. Say you wanted to read a point 4/5th of the way (because that's the sort of rulings on graph paper) between scale markings, see how easy or difficult it is with JTB's good and bad example scales.

As a rider, I always used to get very irritated by students who drew graphs for no good reason, other than they hoped it might earn marks and required little effort or thought on their part, since they had software that did it for them. If you draw a graph for a purpose, then it is usually fairly clear how to do it to best achieve your objective, irrespective of any "rules". Those guidelines seem to be simply an arbitrary low bar, below which one can reasonably say the graph is not serving it's purpose well enough.
 
  • #5
I didn't realize drawing graphs by hand is still assessable??
 
  • #6
houlahound said:
I didn't realize drawing graphs by hand is still assessable??
Why would it be any less assessable now than it has ever been?
 
  • #7
I started a thread on it, don't want to derail this one.
 

FAQ: Having real problems with working out scales for graphs

1. What are the most common types of scales used for graphs?

The most common types of scales used for graphs are linear, logarithmic, and categorical scales. Linear scales are used for displaying data that has a consistent interval between each data point. Logarithmic scales are used when the data has a large range of values and a linear scale would make the graph look too cluttered. Categorical scales are used for data that falls into categories or groups, such as demographic data.

2. How do I determine the appropriate scale for my graph?

The appropriate scale for your graph will depend on the type of data you are presenting and the purpose of your graph. If you are displaying data with a wide range of values, a logarithmic scale may be more appropriate. If you want to show the relationship between two variables, a linear scale may be best. It's important to consider the audience and the message you want to convey with your graph when choosing a scale.

3. What is the difference between a linear and logarithmic scale?

A linear scale is a scale where the distance between each data point is equal. This means that the values on the scale increase or decrease by the same amount. A logarithmic scale is a scale where the distance between each data point increases or decreases by a constant ratio. This is useful for displaying data that has a large range of values, as it compresses the data and makes it easier to interpret on a graph.

4. How can I make my graph more visually appealing and easy to understand?

There are a few tips for making your graph more visually appealing and easy to understand. First, make sure to choose the appropriate scale for your data. Avoid using too many colors or complicated symbols, as this can make the graph look cluttered. Use clear and concise labels and titles, and consider adding a legend to explain any symbols or colors used. Finally, make sure to use consistent formatting and font sizes for a clean and professional look.

5. How can I ensure accuracy when working with scales for graphs?

To ensure accuracy when working with scales for graphs, it's important to double-check your data and calculations. Make sure that your data is consistent and accurate, and that you have chosen the appropriate scale for your data. It's also helpful to have someone else review your graph before finalizing it, as a fresh pair of eyes may catch any errors or inconsistencies.

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