Download Week 2 summary Dr. Ahmed Morshedy Free edition

‫‪PHC 121‬‬
‫‪Biostatistics‬‬
‫‪Week‬‬
‫‪2‬‬
‫‪For‬‬
‫‪Saudi electronic university‬‬
‫‪Dr. Ahmed Morshedy‬‬
‫دهلمهكسوا همدسه ماماس ملاضمهتسيمجمسه لتهصاس م‪ :‬س‬
‫‪002 01015801806‬س‬
‫غيررمسموررمتدسولررذهتاسم ر سه م ص راتستالسيجررتنسرهررمما‪،‬ستم ر هس رريكسملمار راعس ر ‪،‬سفه ر هسمجهررتذس‬
‫لرظيمرر س مررراذلسه ميرر سه ملرررتفملس جميرر ست ررردسورررذهقاقستلمرررت سه م ميرر سه ممميرر س يهررراسمقررراتس‬
‫هألذ ر سمرهررايسلررذيوسه موررتاسﷺس(مررسسورروىسم ررمسمرراس ر سيورروىسم يرردسمور سفهررتس ررد ‪،‬ست ررمهمسمجمر س‬
‫ه ممررردسهموررردم سه رررذت سمررراسي رررمس(هالور ر سه لجرررامالسته دمر ر سه لجامير ر ستسه لر ر ي ستهال لرررمهعس‬
‫تهالولمررامسمرر سلمررت س اصرر سألصررلاوها‪،‬سيصررورس هرراسفرر سه ررم سه م اصررمس يمرر سما يرر سم لوررملس‬
‫لمتاسه راكس هاقستم سه لمت سي لذسوهاسهم اع‪،‬سفدسيجتنسهال لذهءس يها ‪ .‬س‬
‫يجتنسرهمسم هسه م صس(س‪Week 2‬س سوذتسسي ذسم سسمووىس س‬
‫س‬
‫غ ي ر م س م و ح ب ت د ا و ل ه ذ ه ا ل م ل خ ص ا ت و ال ي ج و ز ن ش ر ه ا‬
‫‪1|5‬‬
Why do we want to conduct research?
• We wish to answer interesting questions about the world.
E.g. is smoking related to cancer?
• Research Process ‫مه سرلمظهاسوا لمليبس‬
1. Read relevant literature
2. Generate research idea
3. Generate research hypothesis
4. Design study
5. Conduct study
6. Analyze data
7. Decision about supports for hypothesis
• Literature Review
Reading previously published research in the particular area in which the
researcher wants to do research.
We search for papers published in peer-reviewed journals such as PubMed
• Benefits of knowledge of previous research for researchers
planning to conduct their own research (MCQ)
1. Guide the choice of research questions
2. Can see how others tackled similar research questions
3. Whether or not they might be heading up to a blind alley or if it was
already answered
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‫غ ي ر م س م و ح ب ت د ا و ل ه ذ ه ا ل م ل خ ص ا ت و ال ي ج و ز ن ش ر ه ا‬
• Difference between research question and research hypothesis
Research question:
o May be a little vague in nature
o Usually written as question
e.g. Is there a link between personality and ability to quit smoking?
Research hypothesis:
o Should be much more precise
Hypothesis are written as statements preceded with the words "I
predict.
e.g. I predict that personality affect the ability to quit smoking.
o The sort of research hypothesis will determine the research designs
and the statistical techniques you will use.
• Variables
We might have a concept of health or illness
When we conduct research, we have to operationalize these concepts into
something that we can observe and measure
These measured concepts are called variables
• Types of variables
1. Categorical (Qualitative) variables: variables that it can take are categories
e.g. Sex, Eye color, Nationality, or job
2. Numerical (Quantitative) variable: variables that it can take are Numbers
o Discrete variables
e.g. Number of children, number of beds or number of rooms
o Continuous variables
e.g. Age, Height, Weight, or time
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‫غ ي ر م س م و ح ب ت د ا و ل ه ذ ه ا ل م ل خ ص ا ت و ال ي ج و ز ن ش ر ه ا‬
• Research Design
‫ يم سه سءسفيدسمتسه مه سه جيذسمسسه ملاضملسه لمهيذي سه ثاري س‬research design ‫جنءسها‬
‫ ه م ل مدس مسم هسه جنء‬MCQ ‫ته جنءسهأل يمسمسسم سه ملاضم سققست كس لاسيوق سها‬
(For MCQ)
• Experimental design (describes the variation of info under hypothesized conditions)
• Correlational design (how one variable change as another one changes
• Between-group design (different participants in each condition you are comparing)
• Within-group design (comparing one group of people across a number of different tasks)
• In our research, we might be interested in differences between condition,
e.g., the difference in blood pressure between a non-salt and low-salt group of high
blood pressure patients.
• OR, we may want to focus on relationship between variable, e.g., the
relationship between anxiety and waiting times in an A & E center.
40
30
20
0
10
% Overweight in Society
50
60
- A useful way of representing the relationship between two
variables is to plot a scattergram or scatter diagram.
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‫غ ي ر م س م و ح ب ت د ا و ل ه ذ ه ا ل م ل خ ص ا ت و ال ي ج و ز ن ش ر ه ا‬
0
20
40
60
Average annual income in 000s $
80
• In between group design: groups are usually independent (called
independent groups), that is because a person in one group cannot influence
the results of a person in another group. (MCQ)
• In an experimental study, we manipulate one variable called the
independent variable (IV) and see what is the effect of this manipulation on
another variable which called the dependent variable (DV). (MCQ)
What are dependent and independent variables? (MCQ)
The two main types variables in the experimental studies are the
independent and dependent variable.
The independent variable is the one that can be changed or controlled in the
experiment to examine its effects on the dependent variable, but the
Dependent variable is the one which is being tested and observed or
measured in the experiment.
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‫غ ي ر م س م و ح ب ت د ا و ل ه ذ ه ا ل م ل خ ص ا ت و ال ي ج و ز ن ش ر ه ا‬
‫نياذهت ه ملاب‬
‫ر‬
‫ر‬
Week 2 extra notes ‫بمحاضة‬
‫مشوحة بالتفصيل‬
Types of variables ‫ نياذهت م جنقي‬-1
‫س(مه سرلمظهاسوا لمليب س س‬Levels of measurements
Nominal
Ordinal
Interval
Ratio
1. Nominal scale (For categorical variables)
They are categories but there is also no order to the categories, you
couldn’t say that one category is higher or lower than another.
‫ هندوسي) أو السؤال‬،‫ يهودى‬،‫ مسيجى‬، ‫مثل السؤال عن ه جرك (ذكر أو أنثي) أو ه ذيار (مسلم‬
)‫س (مدخن أو غير مدخن‬
‫عن همصاو سوممضسم يس (مصاب أم ال) أو ه لذ ي س‬
‫ تهمجاواتسالسلل ذس‬Categorical variables‫المشترك بين كل األمثلة باألعلى أنها أمثلة على الس‬
‫يىسلمليبسضمرمسقس س‬
‫أى يمكننا أن نضع اإلجابات بأى ترتيب‬
)‫ أنثي) أو (أنثي – ذكر‬- ‫من الممكن أن نضع اإلجابات ( ذكر‬
‫ومن الممكن عند السؤال عن الديانة نضع بأى ترتيب ممكن وكذلك السؤال عن التدخين واإلضابه‬
‫عن مرض معين‬
2. Ordinal scale (For categorical variables)
Here we have some sort of order to the different categories on our scale.
‫المختلف هنا هو أننا يجب أن نضع اإلجابات بترتيب معين وال يصح تغيير هذا الترتيب أثناء عرض السؤال‬
For example, “The rating scales” that are often used to get participants’
opinions about things.
3. Interval scale (For numerical variables)
• In these sorts of measurement scales the difference between
adjacent points on the scale are equal.
6|5
‫غ ي ر م س م و ح ب ت د ا و ل ه ذ ه ا ل م ل خ ص ا ت و ال ي ج و ز ن ش ر ه ا‬
• Means that the scale we use doesn’t have true 0 point
"‫مثل "ممياكسذمج سه لمهمل س‬
‫ مئوية‬1 ‫ و‬0 ‫الفروقات بين نقاط درجات الحرارة المتتاليه على المقياس متساوية (الفرق بين درجة حرارة‬
)‫ مئوية‬21 ‫ و‬20 ‫مساوى لنفس الفرق بين درجتي حرارة‬
‫ بل‬،‫ال يوجد صفر حقيقى على المقياس (أى أن نقطة الصفر على المقياس ال تنعدم عندها درجة الحرارة‬
)‫هى نقطه اصطالحية ألحد درجات الحرارة‬
1. Ratio scale (For numerical variables)
In this scale we have a true zero point. So, when we can calculate such
ratios.
‫مثل ه تنسسته طتاسته نمس ففى هذه األمثلة نقطة الصفر تمثل انعدام القيمة بشكل فعلى‬
2- Confounding variables: Confounding variables are variables that
are not central to your study but which may be responsible for the effect
that you are interested in.
Random allocation helps us guard against potential confounding
variables.
3- quasi-experimental research.
When you investigate differences between intact groups such as males
and females, or those diagnosed with a disease compared to those
without a diagnoses you are said to be undertaking quasi-experimental
research.
This is not quite an experimental design as you have not been able to
randomly allocate your participants to the conditions that you are
interested in.
4- EVIDENCE-BASED PRACTICE
EBP is that we look at the available research evidence and we base our
plans, behaviors and practice on such evidence.
7|5
‫غ ي ر م س م و ح ب ت د ا و ل ه ذ ه ا ل م ل خ ص ا ت و ال ي ج و ز ن ش ر ه ا‬