S1 Question

http://www.thestudentroom.co.uk/attachment.php?attachmentid=283055&d=1399575911


When working out the area of each bar in a histogram, would you use the class width as the width or the small unit squares as the width? Does it make a difference? I've seen it being used interchangeably.

For example, why in the example above are the class intervals used? Could he not use 1cm by 8cm, for the first block?

And when using class intervals, should you not be aware of whether there are gaps or not between the groups? Can the first bar have an interval of 3? And the second one 4 (1.5-4.5)?

Q5 in the link

That's question 8.

Either should be fine. As long as you are aware that frequency is proportional to area.

As for the second point..there are no gaps between bars. Histograms are use for continuous data. The only time that you get a gap is when you have a zero frequency.

Thanks, really helpful!

I have seen grouped frequency tables for histograms with gaps, but as it's continuous, you'd add the class boundaries right?

Can you give an example of what you are referring to here?

Q1

m.youtube.com/watch?v=Rxkd2X938vg

Yes, in this type of situation you need to work out what the boundaries are. You're more likely to be dealing with rounded continuous data than discrete data though.

Yes, in this type of situation you need to work out what the boundaries are. You're more likely to be dealing with rounded continuous data than discrete data though.