Bianco and Lecce (2016) want to see whether the children who received the ToM intervention have made significant progress over the course of project by comparing their scores before and after the intervention. They have decided to use a Wilcoxon’s test.
2. Calculate the observed value of T by completing the following table and use the space to show the rest of your workings. (5)
The first thing you need to do to answer this question is fill in the correct columns of data into the table. The question refers to “whether the children who received the ToM intervention have made significant progress over the course of project by comparing their scores before and after the intervention” this means toy have to look at the column headings in the table and make sure you choose the correct columns of data to work with. The control group’s data is also in the table. This is because Bianco and Lecce (2016) were also interested to see how much children’s scores change regarding their “theory of mind” over the course of time in the absence of a specific intervention. Hopefully you chose the correct data and your table should look like this:
|Condition A||Condition B||Difference (d) (A-B)||Rank|
- Once you have filled in the data for condition A (before the intervention) and condition B (after the intervention), you have to work out the difference between A and B, doing A-B for each Pp. In my table none of the children made no progress (i.e. A and B were the same). If they had, their “d” score would be zero.
- The next job is to “rank the d scores”; I have made a link here to the page on ranking in case you can’t remember how to do this 🙂 In this case the sign (+ or -) is irrelevant, we are simply looking at the size of the difference.
- The next job is to add up the ranks for any of the Pps who had a positive difference: in this case…
Sum of positive ranks: 1.5+6+1.5=9
4. Then you need to the add up the ranks for any of the Pps who had a negative difference: in this case…
Sum of negative ranks: 6+4+8+9+3+6=36
5. The next step is to identify the smaller if the two numbers. This is your T value! Just remember if any of your Pps scored zero they are not included in this part of the process.
So, in my example the T value is 9 as 9 is less than 36