IB SL Mathematics International Assessment
St. George´s School Munich
Is there a correlation between the number of
hours slept at night and short-term memory
recall in teenagers and middle-aged adults?
Word count: 5.995
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,Table of Contents
I. INTRODUCTION 1
II. THEORY 2
III. METHOD 2
COLLECTING DATA 2
1. CALCULATING MEAN SCORES OF EACH MEMORY TEST 4
2. CALCULATING WEEKLY MEAN SCORES OF EACH PARTICIPANT 5
3. CALCULATING WEEKLY MEAN SCORES OF EACH PARTICIPANT THROUGHOUT THE COURSE OF 4
WEEKS 6
4. CONVERTING SLEEPING TIMES INTO DECIMALS 7
5. CALCULATING WEEKLY AVERAGES OF SLEEP OF EACH PARTICIPANT 8
6. CALCULATING WEEKLY AVERAGES OF SLEEP OF EACH PARTICIPANT THROUGHOUT THE
COURSE OF 4 WEEKS 9
7. SCATTER GRAPH 10
8. EQUATION OF THE REGRESSION LINE OF Y ON X 11
9. PEARSON´S PRODUCT MOMENT CORRELATION COEFFICIENT 11
10. SPEARMAN’S RANK CORRELATION COEFFICIENT 12
11. BOX-AND-WHISKER DIAGRAMS 14
IV. REFLECTION 16
V. CONCLUSION 17
VI. BIBLIOGRAPHY 17
VII. APPENDIX 18
I. Introduction
This investigation aims to find out whether or not there is a correlation between the number
of hours slept at night and short-term memory recall in teenagers and middle-aged adults. I
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, have chosen this topic because I am very fascinated about the importance of sleep and the
way it impacts our health, mood, concentration, productivity, energy and mental functioning
(Weatherspoon, 2019). I believe that, as a modern society, we often neglect sleep and do not
prioritize it enough, myself included. I feel as though we are always busy and on the go, and
spend too much of our time on the phone and on social media. I, as a teenager and student,
often struggle to get adequate sleep, and have realized how a lack of it impacts my day, and
not in a good way. I feel tired, moody, lazy and find it extremely hard to concentrate. In the
past, I have also found it difficult to remember and retain important facts and information
when revising days before my exams, and always wondered whether a lack of sleep played a
role in that or whether other factors did. Though it is very complex, I have also always been
amazed at the way both short-term and long-term memory work, as well as how statistical
analysis can be used in psychology, the subject I want to study at university.
Even though there has been research done indicating that sleep deprivation can indeed
impact memory recall, I decided to combine my interests for both and further explore their
correlation by gathering my own data and bringing forward my own procedure. My null
hypothesis, (H1), is that there is no correlation between the number of hours slept at night
and short-term memory recall in teenagers and middle-aged adults. My alternative
hypothesis, (H0) is that there is a correlation between the number of hours slept at night and
short-term memory recall.
II. Theory
“Memory is our ability to encode, store, retain and subsequently recall information and past
experiences in the human brain” (The Human Memory, 2019). There are three types of
memory: working memory, short-term memory and long-term memory, and in this
investigation, I will be focusing only on short-term memory as it is the one that interests me
the most. Short-term memory is the ability to keep a small amount of information in mind for
a short period of time (Kintz, 2014).
There are three types of recall: serial, free and cued recall test. Serial recall is the process in
which a person is given a list of items and is then asked to recall the items by writing them in
the order that they were given. Free recall is when a person is given a list of items and is asked
to recall them in any order. Cued recall is the process in which a person is given a list of items
to remember and is then asked to recall the items with the use of cues or guides ( (The Human
Memory, 2020).
According to the National Sleep Foundation, teenagers need around 8 to 10 hours of sleep per
night, but a very small percentage of them actually sleep for that long. Teenagers are often
sleep-deprived during the week due to school, and use phones late at night, preventing them
from getting quality sleep. On the other hand, adults need around 7 to 9 hours of sleep per
night. On average, women need 20 more minutes per night more than men (Adoption
Doctors, 2019), and they experience a lighter sleep that is more easily disrupted by problems
such as depression, pregnancy, hormonal changes, sleep disorders, etc. (Kittredge, 2018).
III. Method
Collecting data
Once I decided that my focus on this investigation was going to be short-term memory, I began
to research types of tests that could be used to examine one´s capacity to retain information
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