How To... Perform a One-Sample t Test by hand and in Excel 2016

Yesterday I published a new video showing students how to perform a one-sample t test by hand. This test shows if there is a significant difference between a sample mean and a population mean. My students from next September will need to know how to perform this test by hand. Here's the video:

Today I am publishing how to do the same test using Excel. This has to be done manually step-by-step, as Excel does not have a Data Analysis tool of function to do this test. The same result is obtained - here's the video:

After a sudden burst of creating three new videos, that's it for a while as I am starting holidays from tomorrow. I will be on the lookout for new stats test to cover as I plan on adding some more to my modules next year.

Woodenbridge World War I Memorial Park

1,192 men and women from my native County Wicklow lost their lives in World War I - I did not know this. While leaving the Woodenbridge Hotel after a lovely lunch with my Mum and Dad last Saturday I noticed a sign for a memorial park which is about 50 metres from the hotel. It is located beside the River Aughrim and also on part of the old railway line that ran between Avoca and Shillelagh. The Stonehenge themed format of granite slabs lists the almost 1,200 people from each town and its surroundings in Wicklow, including 12 names from our native Carnew. Many surnames, like Doyle and Byrne, feature on nearly every slab - so many families in Wicklow were affected by the war. My Dad was deeply focused on the familiar names from families that he knew in the Tinahely, Carnew, and Shillelagh areas. Although he was born just 13 years after the war ended, names such as Noblett, Doran, Dowse, and Somers are very familiar to him. 

In the peaceful setting of this memorial garden in Woodenbridge it is hard to feel the horror of the war. Woodenbridge is also the setting of a famous speech when on Sunday 20th September 1914, John Redmond (leader of the Irish Parliamentary Party) urged Irish men to join the British army in the belief that it was for the common good. Little could he have thought that many of those who answered his call would die facing German and Turkish bullets. 1,192 dead Wicklow people (almost one for every day of the war which lasted 1,564 days) is a terrible toll undoubtedly repeated in every county in Ireland.  

My Dad was also interested in the location of the railway line, which he remembers taking in the 1930s and 1940s before it closed. In the photos below you can see the remains of a bridge over the River Aughrim, and some walls on either side of the river are still standing. The railway line opened on 22nd May 1865, but closed for passenger and goods traffic on 24th April 1944. It was finally closed altogether on 20th April 1945. The section from Woodenbridge to Aughrim however remained open until 1953 - part of it today has been redeveloped as a walking route called the "Tinahely Railway Walk".

How To... Calculate Spearman's Rank Correlation Coefficient (By Hand)

It's been a while (four months) since I published a new video on YouTube. My latest one, published today, is a statistics video showing how to calculate a correlation coefficient  - the technique used is based on Charles Spearman's rank-based test. A correlation coefficient tells us the strength (or weakness) of the relationship between two variables. If the data are normal you can use the Pearson's R, but if not - a non-parametric test such as Spearman's should be used. 

I was very rusty making this video and had several re-runs to get it (hopefully) right. This will be a new topic in one of my modules (Advanced Business Data Analysis) next year. Enjoy!

How far will we go to stop cheating using mobile phones in exams?

Anyone taking part in an exam (or even taking part in a quiz) is warned that mobile phones are not allowed under any circumstances in the exam - there are often severe penalties for anyone caught even having a phone on their person, even if they are not using it. It's a simple rule which most people follow. Obviously, there is huge temptation to use a phone in an exam if you think you can get away with it - nip out to the loo and do a quick Google search for an answer. Exam invigilators can't follow you into a loo cubicle. I'm sure smarter people than me can figure out other ingenious ways to use a mobile phone. How can this be stopped? Should honest people be penalised for the dishonesty of others?

Image source: Ysgol Rhiwabon

The Guardian today reports that Algeria shuts down internet to prevent cheating during high school exams. According to this article, "The whole nation of Algeria went offline on Wednesday for the start of high school exams, the first in a series of internet blackouts to stop the possibility of students cheating". Also "mobile phone jammers and surveillance cameras had been installed in locations where the exam papers were printed". Drastic action indeed - the whole country has no access to the Internet for three hours! I don't know anything about the level of cheating in exams in Algeria, but the article does say that the "2016 exam season was marred by widespread cheating, with exam questions published on social media before, or at the start of, the test". I expect that Algeria is not much different than other countries. It was also reported in The Guardian on 18th May that "Iraq shuts down the internet to stop pupils cheating in exams".

Try blocking access to the Internet for even just a few hours here, or in any European country, or the United States!!!

Cheating will always take place, but it is important to stress that not everyone cheats. Some people will have a strong sense of right and wrong, and will just not do it. Others will not do it for fear of being caught, while of course many people will have prepared well for an exam and not need to cheat. My sense is that current measures work very well and that we have to accept that a small minority will still attempt to cheat. Shutting down the Internet is too drastic a measure to work everywhere.

An alternative is to allow use of the Internet in exams!

My thoughts - no one else's.

My Ancestors married often!

Like everyone else, I have eight great-great grand-fathers. One on my mother's side of the family Richard Cullen, whom I have written about before in this blog - he married three times. I discovered this evening, while searching for a link with the late actor Donal McCann, that another of my great-great grand-fathers, James McCann, was married twice. First - he married my great-great grand-mother, Catherine Walsh, in 1869. The genealogy record is not strong on this, but their first son, William, was born in 1870. Their daughter Anne McCann, is my great grand-mother. Catherine (Walsh) McCann died on 2nd May 1908. Eighteen months later, James married Dorah Sheehan - according to the 1911 census, she had a daughter Margaret. Here is a screen grab of their marriage record which can be found at: 

https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1909/10036/5650652.pdf

James McCann died on 28th January, 1927. He is buried in St Michael's cemetery in Gorey, Co Wexford, with his son William and his first wife Catherine. No sign of Dorah in the grave with him, and she is not even listed in the list of People Buried at St. Michael's cemetery.

Continuous Assessment vs Over-Assessment

At the end of another academic year (my 16th!), I can look back on a year where I spent an enormous amount of time grading assessments. This past semester I have three modules with three separate assessments (usually two assignments and an exam). The class size is about 60 students on average - that's approximately 540 assessments to grade. For my remaining module, I have weekly labs that must be graded - so there are about 10 of these over the semester. With a class size of 35, this means around 350 separate sets of corrections.  That's almost 900 assessments to grade - all of this takes a long time! For students, they too often feel that they are constantly under pressure of many deadlines throughout the semester, with something due almost every week.

I'm a believer of Continuous Assessment being continuous (the notion of "repeating" a CA drives me mad!). By this I mean that it should be on a regular basis. It's hard work keeping up with weekly lab assessments, but I feel students get more out of it by building on their learning, and building up their grades on a weekly basis. But where should the line be before I cross over into over-assessment? If students are constantly under delivery deadlines (and the threat of penalties if they miss them), where do they find time to experiment, read extra material, examine case studies, take a break, and of course - prepare for exams? A single assignment, and a single exam seems to be the norm in many modules. This is great if you can use them to assess separate Learning Outcome, but it does not always happen that there is a neat division between Learning Outcomes. Designing assessments can be difficult because it is hard to get the balance right. Reducing the number of assessments takes the pressure off students, but we still need to ensure that the Learning Outcomes are assessed adequately. 

Here's a copy of a slide from a presentation by Jean Hughes (Office of the Vice President for Learning Innovation in DCU) relating to over-assessment, with some good tips to avoid over assessing students

Image source: Slide Player.

My thoughts - no one else's.

Aghowle Medieval Church

Looking north towards the Wicklow mountains from the front door of our house in Ballingate where I grew up, the hill of Aghowle looms large. Despite many years looking across Co Wicklow I had never gone over. My Dad Joe told me about the ruins of a medieval church located there - so yesterday we finally went over in glorious sunshine to check it out.

We found the church easily enough, even though the broken signpost was hidden by weeds at the side of the road. An OPW sign at the site told us that while none of the original monastery remains, it was thought that St Finian from Westmeath had established a monastery there in the 6th century. The ruins you see below date from the mid 12th century - incredible that they are still standing tall (over 10 metres) over 900 years later. 

There are a lot of very old graves dating from the late 1700s according to the headstones. This includes the headstone in beside the ruins where Owen Griffin has lain since 4th April, 1784. There are a handful of burials this century - a more peaceful place to rest cannot be found. There is a beautiful Celtic Cross - I'm surprised it has not been stolen. The most common surnames in the cemetery are Byrne, Doyle, and Keogh/Kehoe. Many headstones pay devotion to Our Lady of Lourdes - there is also some candles and small statues to Our Lady in an alcove that have recently been put there. Later we adjourned to the nearby Crab Lane pub - neither of us had been in it before. A cool beer on a hot day in Aghowle tasted excellent!

Death while in class #BobbyKennedy #memories

Bobby Kennedy.
Image source: Wikipedia.

On this day, 6th June 1968, I was 8 years old and in 3rd class at Carnew National School. Our classroom was a pre-fab building, and our teacher was a Mr Hennessy (what a pity I cannot remember his first name, he had a cool green MG sports car!). There's no way I would have remembered anything about this day except that it was the day that Bobby Kennedy was shot dead in far away Los Angeles. 

Around mid morning, a girl from another class suddenly came into our classroom to tell us that Bobby had been shot, but was still alive. We were all old enough to know who he was. I don't recall if our teacher got us to pray for him, or even if we talked about him. About an hour later, the same girl came to our classroom again and told us that he was dead. Breaking news the old-fashioned way!  The moment was not lost on us little 8 year olds - it was a tragic but historic interruption of our education on a typical day in school.

Bobby Kennedy was just 42 years old when he was murdered. He may never have become President of the United States - who knows even if he would have won the Democratic nomination or beaten Richard Nixon in the 1968 election. To a lot of us, he will always be simply Jack's younger brother. His toothy black and white image is seared on our brains with an "Only the good die young" message to remind us of who he was. 

Fuck you Sirhan Bishara Sirhan, fuck you.

Visiting Belfast #NoBorder

This past weekend I had the pleasure of visiting Belfast once again - since my daughter Vicki went to College there I have been a regular visitor, and I love it. This weekend we went to the Giant's Causeway and a drive around the Causeway Coastal Route. I had last travelled this route on my bike in 2014. 

Brexit casts a shadow from far-away London over Northern Ireland. Some welcome this shadow, while others dread the day next year when the UK leaves the European Union. While Northern Ireland voted 56% Remain and 44% Leave - it will leave the EU along with the mostly grey English vote who have had enough of Europe. Along with many people in Ireland I cannot understand the Brexit vote, and the national self-destruction it brings (from my eye). While driving across the border on the way to Belfast, and later on the way home to Dublin - the borderless border somehow feels natural. In a sense, driving from Co Armagh into Co Louth, feels like driving from Co Wicklow to Co Wexford - only a sign tells you that the two places have different names. 

Along with everyone else, I await the solution that the Oxford/Cambridge trained minds of the UK Government and Civil Service will eventually come up with. I truly believe that some of the smartest people in the world must be able to come up with a solution that works for everybody. The UK government does not yet seem capable of deciding what is best for the UK - but I am hopeful they will. Any kind of border between our two parts in this island must be avoided - but it seems increasingly impossible. I fear for the future and the return of the days when I feel that visiting Belfast will become a memory.

What would Fionn Mac Cumhaill think?

I haven't gone away!

Following my quietest month (just 3 posts in May) since July 2007, I hope to return to writing again this June. I plan some posts mostly about education in the next few weeks as the annual frenzy of grading assessments comes to an end. I have had my biggest classes ever this past semester, which meant a small mountain of grading to do. I feel as though I have been grading non-stop for the past 10 weeks or so. This is now over and there is the summer to look forward to!

Image source: memegen.