Bias and Confounders

Question 1

بسم الله الرحمن الرحيم وبه نستعين
types of errors in epidemological studies

Answer 1

Random Error
Systematic Error:
Selection Bias
Infromation Bias

Question 2

Random errors causes Mention

Answer 2

Due to
Sampling process
مش بيمثلوا المجتمع كله
Biological variations
Measurement process
في القياس زي ضغط الدم مثلا
مستحيل تتخلص من الأخطاء دي بس ممكن تقللها ازاي؟
Increasing sample size
Well Trained Data collectors to decrease Measurement errors

Question 3

Systematic error that may occur in epidemological observational studies is ?

Answer 3

BIAS
Usually in one direction

Question 4

Results of bias?

Answer 4

Under or Over Estimation Of association

Question 5

Types of Bias mention

Answer 5

Selection
Information
Confounding

Question 6

Selection bias definition and mention examples

Answer 6

It is bias due to selecting samples in a way increasing or decreasing the association
________________
VH3PLo
-Volunteer bias
مثلا بتعمل بحث عن مرض الكبد فالناس اللي شاكين ان عندهم المرض هم اللي هيجيجوا مش هتمثل المجتمع كله
-Healthy worker effect

-Prevelant cases Nyeman Bias
-Hospitalized cases
-Cases from specialized hospital or university
-Loss of cases during follow up

Question 7

Informatin bias mean and mentio examples

Answer 7

Means information collected in wrong way leading to misclassificatioon according to exposure and outcome or both
_______________
SI2R2
Survillance or detection bias
Inter and intra observer
Recall bias
Reporting Bias

Question 8

How to Control Informational bias
?

Answer 8

BSQA
1-Blinding the interviewers or investigator from case /control or exposed / non exposed status of a gives participant
_________________________
2-Form of survey :-
Mail survey impose less “White coat HTN’ than a phone or face to face survey
_______________________
3-questionnaire: multiple questions for the same information for double check
____________________
4-Accuracy :
-Multiple check of information in medical records
-Make sure of diagnosis data from different sources

Question 9

Design , data collection & analysis should be done by proper technique to reduce ?

Answer 9

Bias

Question 10

Confounding factors is ?

Answer 10

Situation in which the asscociation between Exposure and outcome is distorted by third factor related to both and accounts for some or all the observed relationship between both

Question 11

The associations of confounding factos mention

Answer 11

Associated with the exposure without being one of its consequneces
Associated with the Outcome indepedneltly of exposure not intermediary
زي التدخين في الناس اللي بتشرب قهوة هو اصلا عامل مسبب لسرطان البنكرياس حتي في الناس اللي مش بتشرب قهوة والقهوة مبتحلاش من غير سجارة علي راي الشاهد يبقي هو مرتبط بمين ومين ؟ بالقهوة والسرطان فهو confounding

Question 12

realation of maternal age with birth order and Down syndrome ?

Answer 12

عمر الأم مرتبط بترتيب الولادة
وفي نفس الوقت هو عامل خطر لمتلازمة داون حتي لو تريتب الولاد قليل مش كبير
إذن فهو
cONFOUNDING

Question 13

Alcohol and smoking and lung cancer

Answer 13

التدخين مرتبط بالشرب وحتي لو مش بيشرب فهو مرتبط بسرطان الرئة إذن فهو
Confounding

Question 14

Nyeman bias

Answer 14

Prevlant cases with survior factors
we need fresh diseased in acute state

Question 15

Berkson Bias

Answer 15

hOSPitalized cases with other diseases affcting study

Question 16

Attirion Bias

Answer 16

Loss during follow up as cohort studies and clinical trials as a rule of thumb

Question 17

المرض بيتفكروا اكتر من الاصحاء ده اسمه ؟

Answer 17

recall bias

Question 18

الناس بتتحرج او بتمنتع عن الاجابة بسبب قيم اجتماعية وغيره ده اسمه ؟

Answer 18

Repotring Bias

Question 19

جامع البيانات بسأل اسألة بطريقة تخلي الشخص منحاز لاجابة معينة
او ان جامع البيانات منحاز لاجابة
يبدل نبرة صوته او لغة جسده وتعبيرات وشه ده اسمه ؟

Answer 19

Interviewer Bias

Question 20

بعض المستشفيات نظام المراقية الصحية فيها اقوي من غيرها دي يؤدي لانه الناتج المطلوب من الدراسة يظهر بشكل اكبر ده اسمه

Answer 20

Survillance Bias

Question 21

Detection bias and inter observer bias

Answer 21

DETECTION اختلاف الأدوات
INTER Observer اختلاف طريقة استخدام الأدوات

Question 21

Detection bias and inter observer bias

Answer 21

DETECTION اختلاف الأدوات
INTER Observer اختلاف طريقة استخدام الأدوات

Question 22

Critera of questionnaire to control bias

Answer 22

Mutliple questrionns for same information double check
Multiple sources of information
Standard Measrument instruments as questionnaire ,devices

Question 23

Control of selction bias how ?

Answer 23

-Random selction of smaple
-Never select samples from same depatement of disease intended
-Using incidence not prevelant cases

Question 24

Reduce systematic erros leads to ?

Answer 24

Increasing validity of study

Question 25

Mention Charcteristics of Confounders

Answer 25

1-Risk factor for disease
2-Assoicated with Exposure but not result
3-not intermdeiate between exposure and outcome

Question 26

رب اغفر وارحم وانت أرحم الراحمين

Question 27

Random errors cannot be elimniated how can you rduce ?

Answer 27

a. Larger sample size,
b. Taking the average of at least 2 measurements (e.g. Blood pressure)

Question 28

Random errors cannot be elimniated how can you rduce ?

Answer 28

a. Larger sample size,
b. Taking the average of at least 2 measurements (e.g. Blood pressure)