This is my third question:

3. Are there more 9s in the lower grade level, Standard 4?

I'm going to use Lertap's "Breakout score by groups" option to answer this one.

The groups will be grade levels, Standard 4 and Standard 5, coded in column 2 of the Data worksheet.

The "score" will be the number of unanswered questions. I've called this the "9s" field; it's found in column 29 of the Data worksheet.

The breakout option is happy to have the "groups" information in the Data worksheet, but it wants the "score" to come from the Scores worksheet. I need to copy Data column 29 to the Scores worksheet.

Is this hard to do? Is having a fresh, strong coffee first thing in the morning hard to do? Answer to both these Qs: no.

I take the first option from the Move menu, and before you can recite the names of my neighbor's children, dog, and egg-laying hen, my Scores worksheet looks like this:

The first score, "BSci3.4", is test score; in this case, it is the number of items answered correctly. Since there are 24 items, the "MaxPos" (maximum possible) score is 24.00.

The second score, "9s", is the number of unanswered questions. The "MaxPos" is also 24 for this score, but I note that "Max", the maximum 9s score, was 23.00, meaning that all of these students answered at least one of the 24 items.

Pause for a moment to consider the correlation between the two scores. It's -0.61. This makes a lot of sense; students getting the higher test scores tended to have a lower 9s score, that is to say, unsurprisingly, students who failed to answer items tended to have a lower test score.

Now I am set to use that mighty "Breakout score by groups" option. It makes this little report for me:

I see that the average number of unanswered questions in Standard 4 was 5.05, compared to 2.66 in Standard 5. Yes, it seems there were more 9s in the lower grade level.

But I'm not satisfied. I know that I can get Lertap to give me more information. Please, Lertap, could I have a histogram of the 9s score for each group?

With the Breaks1 report showing (as above), I click on "Histograms".

Here are the results for Standard 4 (I have not copied the whole histogram; some of the frequency bars extend much more to the right):

How many Standard 4 students left 12 or more items unanswered? I drag my mouse down the "f" column, from a score of 12 to a score of 23. When I do this, Excel adds "Sum: 322" to its Status bar, so Answer = 322. This is equal to 19.7% of the Standard 4 students.

Here are the results for Standard 5:

How many Standard 5 students left twelve or more items unanswered? I drag my mouse down the "f" column, the score frequency column, from a score of 12 to a score of 23, and, looking at Excel's Status bar for "Sum:", I find that Answer = 181. This is equal to 10.3% of the Standard 5 students.

3. Are there more 9s in the lower grade level, Standard 4?

You bet! Compare the two percentages: approximately 20% of the Standard 4s left at least twelve questions unanswered, compared to about 10% of the Standard 5s.

Reliability is next.