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Shape
Shape
Often the shape is not perfect, therefore use words like "tends towards.."
To justify the shape, think about the following features:
Symmetry
Number of peaks
What shape the tails are
Example:
Example:
For my sample, the year 12 bag weight tends towards a normal distribution with a peak at 6kg, however it has a slight left skew. While for year 9 bag weights are right skewed with a peak at 3kg an outlier at 13.5kg. The next largest value is 8.5kg.
Centre
Centre
To describe the centre of your samples:
What is each groups' median?
Which groups median is bigger and by how much?
For Merit, you need to add the justification and evidence.
What does this mean?
If one group is larger than the other it means they they tend to be larger. It does not mean they are larger.
Example:
Example:
For my sample, the median bag weight for year nine students is 4.75 kg and the median bag weight for year thirteen students is 3.25 kg. Therefore year nine students' median bag weight is 1.5 kg heavier than the year thirteens'.
This means that median for bag weight in year nine tends to be larger than year thirteen which means that year 9 students are often taking heavier bags to school with them than year thirteens'. This could be because in year nine the students are more diligent and keep all of their required equipment in their bag all the time, while year 13 students firstly have less subject but also may only bring a book when they are going to need it.
Interesting/Unusual Features
Interesting/Unusual Features
This could be an interesting point, cluster of points, or gaps in the data.
Identify where the interesting features occur, and give a possible reason why these might occur.
There might NOT be interesting features, so if there isn't don't comment on them.
Spread
Spread
Find the IQR, and tell me which group’s spread is bigger and by how much.
For Merit, you need to add the justification and evidence.
Example:
Example:
In my sample, the interquartile range (IQR) for year nine student bag weight is 2.25 kg, while the IQR for year thirteen student bag weight is 3.5kg. Therefore year thirteens' have an IQR that is 1.25 kg larger than the year nine students' bag weight.
This means there is more variation in year thirteen bag weights than year nine bag weights. A reason for this could be the difference in year thirteen students. Some students may take subjects that require different items to be carried between school and home such as textbooks, where as some students may take practical subjects with no equipment that is taken home. This could be one of the reasons to account for the larger variation in year thirteens, while year nine students often have more similar subject to one another.
Shift/Overlap
Shift/Overlap
Is one of the middle group's middle 50% shifted higher up the axis than another
Do the middle 50% of each group overlap? If so how?
Example:
Example:
For my sample, the year nine bag weights' middle 50% is shifted higher up in weight compared to year thirteen bag weights. Evidence of this is seen with the year nine bag weight upper quartile (UQ) of 6.25 kg being higher than the year thirteen UQ of 5kg. This is as well as the year nine bag weights' lower quartile (4 kg) being higher than the year thirteens' median of 3.25kg. This shift of the year 9's further up the show bag weights tend to be higher, however there is still an overlap in the middle 50%.
Practice for yourself!
Practice for yourself!
With the graph, below have a go at describing the features. Once you have completed them, email them for checking with your teacher.
With the graph, below have a go at describing the features. Once you have completed them, email them for checking with your teacher.
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