research scipts

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Ya3teekom 2l 3afye, menra77eb fiku marra 2o5ra and

first of all I am VERYY happy to see you again and to

have the honor to teach you this course in your third

year (its an honor for us dr.), I was happy to teach

you three of the most important courses that are

needed basically for each dentist student; oral

histology, dental anatomy and oral physiology.Congratulation for those how could pass the second

year and are now studying in the third year, I will teach

you another course which has a different topic, it is

related to create from you a Researcher and this course

is called Research Methodology or Research

Design in this curse we will teach you how to havethe ability or how to handle the basic principles of

research methodology, because we dont want you just

to practice dentistry we also want these dentist to do

researches, and it is because of research that

developing takes place, without research, believe it or

not, the dentistry profession will stop at some stages!

As a university lecturer, I am not only a lecturer, I amalso a researcher, but unfortunately a lecturer in the

developing countries like Jordan are more lecturers than

researchers, but in fact if you go to any lecturer in any

western country, you will find that this lecturer is also to

fifty percent a researcher, but we are trying our best to

do researches.

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I am doing now a number of researches, and actually

we are achieving big success in researches, the biggest

success of my researches was while I was teaching you,

it was about the Chronology of tooth eruption, so lastyear we studied the timing of tooth eruption according

to studies found in Europe and America but we didnt

have any studies done in Jordan so I did the first one,

this will be available soon inshalla, so those who are

now in the second year will learn the chronology of

eruption according to the Jordanian population.

Slide (2): Research fields in medicine

In medicine we have different sciences; we have

biological sciences, clinical sciences, population

sciences, and health service sciences

B iological sciences: like anatomy and physiologyand etc

Those sciences, which are related to diseases, focus

on the basic knowledge and information in a specific

field, for example when I tough you dental anatomy I

was providing you every information that you need to

know about the shape of the teeth. And you will learn

the information about how a disease occurs in thefield of oral pathology; these are examples of

biological science.

Clinical sciences : is when you start to apply theinformation

that we toughed you in the clinics. For example the

science of making a filling (restorative dentistry) or

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the science of treating an inflamed gingiva

(periodontics) are clinical sciences, they will serve

individual patients and you are trying to benefit that

particular patient.

Among the clinical science is what we call clinical

epidemiology; epidemiology, in general, is the study

of disease occurring in human population, for

example AIDS, H1N1, gingivitisetc, IF the disease

that I am studying will serve individual patients it will

be called clinicalepidemiology.

Health services: it is the Study of how non-biological factors affect

the patients health. An example of non-biological

factors is the lack of health services, for example if an

ambulance needs two hours to take a patient and

bring him to the hospital the patient may die. So

studying the effect of the lack of services on the

health of the patient is called health services science.

Slide (3): Clinical epidemiology

Clinical epidemiology: It is the science of making

predictions about individual patients; we want to study

the progress of a disease in an individual patient.

It is done by counting clinical events of similarpatients; for example I will examine people havinggingivitis and I will study the clinical events, and Iwill try to count these events by using strongscientific methods, so I cant just study and giveestimation and thats it! After collecting data from

the people I am examining, I have to build goodanalysis and good statistics which are based on

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scientific methodology, it cannot be donehaphazardly! Because the information that thisresearch give, will benefit the individual patient, wedo that because we want to ensure that the

predictions are accurate.So depending on the information provided by thisexamination we can predict what will happen foranother patient suffering from the same disease, soif we are treating another group of patients withgingivitis, we can predict that they will be healthyfor example in three month of treatment.

For any field to be considered as clinical science,the final outcomes have to be applied to individualpatience.

Slide (4): Purpose of clinicalepidemiology

Purpose of clinical epidemiology is to:

1- Develop and apply methods of clinical observationthat will lead to valid conclusions, by avoiding beingmisled by systematic error and the play of chance.

All the time as any researcher you have enemies,the enemy of any researcher is the error andchance, we dont want the chance and thesystematic error to play a role in our analysis ofdata, all the time we try to minimize the role ofthem as much as possible, and eliminating themwill be the best, by avoiding this you will get trueresults.

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2- To obtain the kind of information that the cliniciansneed to make good decision in the care of patients.

After doing a research on the treatment of gingivitis

we could say that people suffering from gingivitiswill be healthy after three month of treatment, thispiece of information is important, it is a conclusionthat will be used by another dentist working byanother place, because he will know that in aprevious research that people undergoing gingivaltreatment will become healthy in three month, sohe will try to apply this conclusion on his patient. Soclinical epidemiology is important for helping theclinicians in making good decisions in the care oftheir patients.

Slide (5): Clinical epidemiology

Why is clinical epidemiology clinical?

Because it answers clinical questions, and it guides

clinicians for making decisions.

Slide (6): Evidence-based medicine

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Evidence-based medicine: is a term that we use

when we apply clinical epidemiology to the care of the

patient.

Evidence-based means that we need to have evidence,

we cannot build a conclusion without evidence.

It has been already proved that smoking is the

cause of lung cancer, we cannot say that just

because we note that people who smoke have lung

cancer, they may have lung cancer because of anothercause, so we took samples and we tried to isolate all the

other factors and we studied the effect of smoking

particularly in the effect of lung cancer, and we proved

by strong methodological evidence that smoking causes

lung cancer, so it has to be evidence based, you cannot

provide a conclusion of a research without an evidence.

Slide (7): Basic principles

The basic principles of any clinical research include first

of all the (1) clinical questions, you have to ask a

question before you start any research, and then you

have to identify the (2) variables.

In my research The chronology of tooth eruption in

Jordanian population the question that was needed is

Do we need to know the timing of eruption in the

Jordanian population? and the answer was YES,

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because we dont have any data for the eruption in the

Jordanian population, the variables that we have are for

example the age, because we will examine people

belonging to different ages, gender is another examplebecause we will examine females and males, we may

want to target for example the private schools only, this

is a variable too, so we have generally two types of

variable, dependent and independent, I dont want to

discuss the difference between these two now, but it

will be covered in one of the coming lectures 2nshalla .

Now after the question and identifying the variables you

will see the (3) outcomes of the research, are the

outcomes important? Are you doing a significant

research?

Is it important to know who is taller, the males or

females?? No, because we already know that males

are taller than females (HE3 :P), so any research

about this topic is not important! It doesnt need all this

amount of money and all that effort to do, so this is a

stupid research and has no outcomes on the health at

all. But in my research (the timing of eruption) does ithave any health outcomes? For example if a patient

comes to you and say my son is one year old and no

teeth came out till now! When I referred to the

European data we discovered that this is abnormal, but

referring to the Jordanian data this was normal, so by

knowing your data in specific, you will check if the child

is having a problem or not, so this is a significantresearch.

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Then we have to look at the (4) numbers that we have

in the research, and the probabilities, we will discuss

this soon.

Slide (8): Clinical question

Each research has at least one question, what question

can be asked?

Is the patient sick or well, is he abnormal or

normal?

How accurate are tests used to diagnose disease

(diagnosis)

How often does a disease occur (frequency)

What factors are associated with an increased risk

of disease (risk)

What are the consequences of having a disease

(prognosis)

How does treatment change the course of disease

(treatment)

Does an intervention on well people keep disease

from arising (prevention)

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did a study on people suffering from liver cancers,

isolating all the others factors, and then he notes that

90 percent of these people died, we built the probability

on a clinical study done previously, thats why we needresearches to help us in treating our patients.

Slide (11): Population and samples

Population: All people in a defined setting with certain

defined characteristics. for example if we want to study

the Jordanian population without any specific

characteristics we say the Jordanian population, it

includes anybody who live in the Jordanian population,

but lets say I dont want to study only the Jordanian

population, I want to study a specific population, I wantto study those Jordanians who are living in irbeT (:P), so

this is a specific population so you have to define the

settings, if you dont define it, this may mean the whole

population of the universe!

Examples are general population (all the population) orhospitalized population (people in a hospital), or if I

want to study those who have a clicky TMJ, this is a

population with a specific disease or observation.

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Sample: Is a subset of people in the definedpopulation, not the whole population, it is not practical

to test all the population.

In my research, the ideal situation was to examine all

the Jordanians whose teeth are in the erupting process,

but can I study three million people!!! Impossible, so I

selected a sample from this population and this sample

needs to be represented in the research.

Selection should not be haphazard; it has to be based

on scientific method, thats why clinical research is all

the time carried out on samples.

The samples make inference about the population So

when we study the sample, the conclusion that we get

from that sample can be applied to that population, and

in my research (the chronology of eruption) I studied all

the schools in Jordan, HOW? I selected randomly fife

schools from Irbed, Zarqa, Ammanetc, so I select

certain number of schools, and then for each school I

dont examine the whole school, I took three students

from each class, so this is a sample, and a sample has

to be randomized and has to be represented, so a good

research is the one whose sample is 100 percent

representative of the population.


Two important points in selecting the sample (1) Are theconclusions of the research correct for the people in the

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sample?? This is important, first of all the conclusions

that I have, have to be correct for that sample, now if

actually the results are correct for that sample then I

ask the second question(2)Does the sample representfairly the population of interest? If yes, then the

conclusion of that sample will be the same as the

conclusion of the whole population.

Slide (14): A sample is representative

A sample is representative: that Depends on how a

sample was selected, if I for example selected justpeople in Irbed, I cannot say that this represent the

whole population, because the sample was not properly

selected, there should be equal chance for all members

to be selected.

Computerized programs now are available for giving

you the principles of how to select a sample.

Slide (15): Bias

Bias: A process at any stage of inference tending to

produce results that depart systematically from the true

values; so any factor during the conducting of aresearch that leads to give untrue values is called bias,

for example in my research about the timing of

eruption, if I only included males, and then I published

my research as it was based on males and females, this

is bias, because it is not true, females may have

different eruption time than males, this leads to the lack

of truth.

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Or it can be defined as any trend in the collection,

analysis, interpretation, publication, or review of the

data that can lead to conclusions that are systematically

different from the truth.

Categories of bias:

Selection bias

Measurement bias

Confounding bias

Slide (17): Selecting bias

Selection bias: Occurs when comparisons are made

between groups of patients that differ in ways other

than the main factors under study.

For example if you are examining dental caries among

dental age groups, it is not correct to examine caries

among different age groups together, and then publish

the results, because the rate of caries in children is

different from the rate of caries in the old people, so Ihave to study caries in the young people, and I have to

specify an age group.

Another example is if you are examining the periodontal

tissue without adjustment for smoking, or the gingival

health without looking for smoking, smoking is

important!!! (the doctor said that I swear :D ), so if I

want to study the gingival health I have to isolate

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smokers from non smoker, I cant mix them, because

smoking affect the health of the gingiva, so it has to be

considered. So any bias based on the methodology in

selecting is called selecting bias.

Slide (18): Measurement bias

Measurement bias: you have already selected the

sample, and now you want to measure that sample, thisbias Occurs when the methods of measurement are not

similar among different groups of patient.

How do we examine dental caries? We examine it

either clinically (looking to the patients mouth), or we

can take radiographs, it is wrong to do research wereactually you have examine one group clinically, and

another group radiographically, you have to isolate this

factor.

Another example is when you are examining the

working length of the roots using different techniques.

in root canal treatment we have to measure the length

of the root, we call it the working length, so we havedifferent methodology in estimating the working length,

if you want for example to study the working length in

some tooth, you have to use only one methodology, or

you can use two methodology but you have finally to

compare the results.

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Slide (19): Confounding bias

Confounding bias: Occurs when two factors orprocesses are associated or "travel together and the

effect of one is confused with or distorted by the effect

of the other, here we have a factor that has been

studied and you didnt pay attention to another factor

which is important and can affect your results.

Example: triglycerides (TG) and cholesterol levels are

associated with risk for coronary heart disease, so if wewant to study the effect of cholesterol on coronary heart

disease it is important to remember that TG can affect

the level of cholesterol, so we cannot study only the

cholesterol on heart disease without studying the TG.

Another Example: Education and/or income with good

health, generally educated people have good health,but why do they have this good health? Is it because

they have better income and they can look after their

body? Or is it because the income allows them to be

educated, to become aware about their health? So we

cannot study the effect of education on good health

without studying the role of income, so we cannot

ignore the important role of income when you study thesignificance of education on good health.

Another good example is the effect of the people taking

folic acid to lower the rates of colon cancer, we actually

ignore an important thing, people who take folic acid

usually take multivitamin, so these are people who areaware about their health, because of that those people

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actually eat properly, do exercise, and know how to look

after their body, so here we ignore the health

awareness because we only study folic acid and know

that it lower the rates of colon cancer without lookingthat these people are already educated, so it is one of

the confounding bias.

Slide (20): Confounding bias

A variable is not confounded if it is directly along the

path from cause to effect, if you get a variable that is

directly from cause to effect and no other factors affect

this pass then it will not be confounded, but if there is

any variable that will affect the pass it will be

confounded.

A confounding variable is not necessarily a cause itself,it can be an effect, for example the healthy people look

after their body, and thats why the take folic acid and

have lower rates of cancer, now the health awareness

has nothing to do with colon cancer but it Is associated

with it, so it is not necessarily the cause of avoiding the

colon cancer.

Slide (21-22-23-24)

Selection bias is an issue in patients selection for an

observation, and so it is important in the design of a

study.

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Confounding bias is an issue in analysis of the data, and

measurement bias is an issue when you are measuring

in your patients.

So each bias is related to some stages in a research, the

first stage which is the selection of samples or research

design deals with the selection bias, the second stage

which is the collecting of data and measuring this data

this is measurement bias, and the final stage of

interpretation of the results is the confounding bias.

Often in the same study more than one bias operates,sometimes we have more than one bias not necessarily

just one of them, in some cases you may have the three

bias together.

A distinction must be made between the potential for

bias and the actual presence of bias in a particular

study; we need to be able to say if there is an actual

bias in your study or there is a possibility of a bias in

your study, you need to be able to distinguish between

these two things.

Dealing with bias: as a good researcher you have to

be able to identify the presence of bias, and then you

have to measure the effect of the bias on your

conclusion, if you think that the effect is very small youchange the conclusions in a clinically meaningful way,

BUT if you think that the effect of this bias is huge than

you have to modify the research design.

THE END

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This work is dedicated for our amazing dof3a

And especially for the medicine student mo7ammadziad darabseh

DONE BY:

AMMAR ANAGREH

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