Variables - Isfahan University of Medical Sciences · INS12 344 Ranking scale A nominal scale with...
Transcript of Variables - Isfahan University of Medical Sciences · INS12 344 Ranking scale A nominal scale with...
Variables
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Lecture Objectives
What is a variable?
Why discuss about variables?
Types of data
role of variables
نام متغيرنقش متغير
واحد نوع متغير
اندازه گير ي
روش
اندازه گير كيفي كمي ي
What Is a Variable ?
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A characteristic varies
It is recorded in our study
نام متغيرنقش متغير
واحد نوع متغير
اندازه گير ي
روش
اندازه گير كيفي كمي ي
Types of Data
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Continuous (پيوسته)
Discrete (گسسته)
Ordinal ( رتبه ای)
Nominal ( اسمی)
Numerical ( کمی)
Categorical ( کيفی)
Scales of Measurement
علمی -1
غ ق جمع -2
جامع -3
رده کافی -4
مناسب -5
رده ی تعريف شده -6
قوی -7
Scales of Measurement
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Nominal
Ordinal
Interval
ratio Numerical ( کمی)
Categorical ( کيفی)
Nominal
Ordinal
Interval
ratio
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Classificatory
Names
Labels
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Ranking scale
A nominal scale with an implicit order
relationship among the measurement
The difference between two adjacent
categories is not the same through out
the scale
Nominal
Ordinal
Interval
ratio
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The unit of measurement and the zero
point ) starting point ) …..
The zero point does not mean the
lack of the characteristic
Nominal
Ordinal Interval ( فاصله ای)
ratio
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A true or absolute zero
The ratio between two values is a
meaningful measure of the relative
magnitude of the two measurements
Nominal
Ordinal
Interval Ratio (نسبتی )
Scales of Measurement
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Nominal
Ordinal
Interval
ratio Numerical ( کمی)
Categorical ( کيفی)
Examples …
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•Drug type
•Hb concentration
•Prevalence of Hepatitis B
•Amount of pure drug in different types of Ampicillin
•Number of deaths in year 1390
•Mortality
•Blood pressure
نام متغيرنقش متغير
واحد نوع متغير
اندازه گير ي
روش
اندازه گير كيفي كمي ي
Types of Data
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Continuous (پيوسته)
Discrete (گسسته)
Ordinal ( رتبه ای)
Nominal ( اسمی)
Numerical ( کمی)
Categorical ( کيفی)
نام متغيرنقش متغير
واحد نوع متغير
اندازه گير ي
روش
اندازه گير كيفي كمي ي
Roles of Variables
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Main variable
Independent variable
Dependent variable
Background variable
Interventing variable
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A B
•Independent variable
•Dependent variable
•Background variable
•Extraneous variable
•Confounding variable
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A B
•Independent variable (مستقل )
•Dependent variable
•Background variable
•Extraneous variable
•Confounding variable
Exposure
Treatment
Risk factor
Cause
Study factor
predictor
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A B
•Independent variable •Dependent variable (وابسته)
•Background variable
•Extraneous variable
•Confounding variable
Outcome
Disease
Effect
Event
Response
Criterion
Exposure
Treatment
Risk factor
Cause
Study factor
predictor
Chocolate
consumption
Nobel
prizes
NEJMon1211064
UV Airborne pathogen
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A B
•Independent variable
•Dependent variable •Background variable ( زمينه ای)
•Extraneous variable
•Confounding variable
Background variable
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L - DOPA Parkinson
•Independent variable
•Dependent variable •Background variable ( زمينه ای)
•Extraneous variable
•Confounding variable
Patients attitude
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Cigarette Stroke
•Independent variable
•Dependent variable •Background variable ( زمينه ای)
•Extraneous variable
•Confounding variable
Sex
Examples …
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•Bladder cancer . Vit A
•MI . HLP
•Lung cancer . smoking
•IQ . Fe
•Thyromegaly . Water iodine
•Blood group . Diabetes
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A B
C
•Independent variable
•Dependent variable
•Background variable •Extraneous variable (مزاحم)
•Confounding variable
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HLP MI
Smoking
•Independent variable
•Dependent variable
•Background variable •Extraneous variable (مزاحم)
•Confounding variable
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Hot tea E. cancer
Smoking
•Independent variable
•Dependent variable
•Background variable •Extraneous variable (مزاحم)
•Confounding variable
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A B
C
•Independent variable
•Dependent variable
•Background variable
•Extraneous variable •Confounding variable (مخدوشگر)
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coffee MI
smoking
•Independent variable
•Dependent variable
•Background variable
•Extraneous variable •Confounding variable (مخدوشگر)
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Opium IQ
smoking
•Independent variable
•Dependent variable
•Background variable
•Extraneous variable •Confounding variable (مخدوشگر)
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gender Coronary
disease
smoking
Intermittent ( واسطه ای)
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diet Coronary
disease
LP
Intermittent ( واسطه ای)
جدول متغير ها
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•Numbers of variables
•Qualitative Quantitative
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We think that Isfahanian
multipara women are at risk of
Anemia more than usual.
Anemia / Number of past pregnancies
Poor culture / Gender / City
Learned or Not ?
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What is a variable?
Why discuss about variables?
Types of data
Scales of measurement
role of variables
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