biostatistics data and sampling nmu

quizzzzzzzzzzzzzzzzzzzzzzzz until we meet again : )

statistics (biostatistics) is ?

the science of collecting,summarizing,presenting,analyzing and testing data for accuracy and significance by statistical methods to make inference and to take a decision (سؤال اوفر ومش مهم غالبا متضيعش وقتك فيه افهمه بس )

statistics means (اجابه قصيره متوقع توقع بسيط تيجي)

facts from figures

importance of statistics 7

simplifies mass of figures (reduce volume of data)

presenting data

facilitates comparison

helps in formulating and testing hypothesis

helps in prediction planning and adminstration

helps in formulating of suitable policies

serves in measuring the standards of health

(مش مهم تكون حافظها فهمها كفايه لان السؤال اللي ممكن يجي هنا يتحل بالعقل لو فاهم )

statistics is classified into 2

descriptive and analyitical (inference) statistics

descriptive statistics is

numerical and graphical description and summarizing of data : tables and graphs central tendancy dispersion

analytical (inference) statistics is

inferential statistics is a technique used to draw conclusions and trends about a large population based on a sample taken from it

about data collection from where data is collected (اعتقد ملوش لازمه )

data can be collected from the total population or a sample of the target population

data vs information (لازم تكون عارفها كدا كدا ) الاتنين في نفس الكارت عشان لو جه في نقطه مقارنه لاوم نربط بين الاتنين

Data consists of discrete observations or events that carry little meaning when considered alone and are inadequate ( غير مناسب ) for planning.

while

Information is a reduced, summarized and adjusted data, to be used for comparison over time and place.

primary vs secondary data

primary data are collected directly from the individuals e.g. census data, while

secondary data are obtained from outside source e.g. published primary data (reports and research).

commonest softwares used for data entry and analysis are 4 ?

SPSS

Epi-info

SAS

excel

variables are

a characteristic, observation or event which assumes different values in different individuals (item of data that can be observed or measured on individuals). لو فاهمها فكك من الافوره دي

data is divided into two types

quantitative (numerical)

and qualitative (catagorical) data

quantiative (numerical) data is divided into 2 types ?

discrete and continuous data

nominal qualitative (catagorical) data is divided into 2 types

binary and multiple data

qualitative data is divided into 2 types

nominal and ordinal

continuous quantitative data is sub divided into 2

interval and ratio

discrete quantitative variables are ?

discrete numbers without fractions (separated) that are counted (nothing in between them)

discrete quantitative variables examples are 4

number of students number of patients heart rate and respiratory rate

continuous quantitative variables are ?

numerical values which may have fractions (تحت may الف خط) and is measured on a continuous scale (uninterrupted range of values)

continuous quantitative variables are sub classified into 2

interval and ratio

interval sub field of continuous quantitative variables is ? and examples

numerical values without a true zero point 0 dooes not indicate a complete lack of the quantity being measured

ex: degrees celsius or fehrenheit

continuous quantitative variables examples

age ,height, weight, blood, pressure, hemoglobin, and temperature

ratio sub field of continuous quantitative variables is ? and examples

numerical values with a true zero point 0 indicates a complete lack of the quantity being measured

ex: age height weight blood pressure and distance

qualitative (catagorical) type of variables is sub classified into 2 (اختلف عن اول صفحه فا التفريعه بتاعت اول صقحه الاتنين تحت اسم واحج هنا وهيتفرعو منه لو مش فاهم dm)

nominal and ordinal

nominal type of qualitative (catagorical) variables are ?

and they are sub classified into 2 ? and explain each

no natural order and sub classified into

binary (dichotomous) : 2 catefories yes/no gender male/female

multinomial: more than 2 categories blood group (a b ab o) diagnosis : diabetes hypertension etc. occupation ? مش عارف اخر واحده دي اي اللي يعرف ياريت يقول لي

ordinal qualitative (categorical) type of variables can be ?

ex ?

can be arranged in orders (ascending or descending)

ex: social class cancer staging educational level degree of anemia (mild moderate sever)

اول سلايد في ال sample اعتقد صعب يجي منه سؤال وانا مش عارف اجيب منه اي فكره ايا كان هو موجود مكان الاجابه بص عليه بردو

the target population is ?

it is the practical accessible population who we actually sample from

the sampling frame is

how we list the sampling frame what info we may have about them to conduct our study from a sample from them ?

a listing of the members of the target population from which the sample is drawn from using the telephone directory

sampling is

sampling should be

• The selection the study sample form the target population using the sampling frame

it should be representative of the population in question

the sample is?

a good sample will ?

• It is a subset of population that is used to gain information about the entire population:

• A good sample will represent the population well.

sampling is classified into two major types

probability and non probability

non probability sample is

and its types are

Every individual in the target population does not has the same chance of being represented (selected) in the sample. • The results will not be correctly generalized to the whole population

its types are

qouta sample

convenience sample

snowball sample

probability sample is

its types are

• Every individual in the target population has an equal chance to be represented (selected) in the sample. • The results can be generalized to the whole population.

1.Simple random sample.

2.Systematic (pseudo-simple) random sample

3.Stratified random sample.

4.Multistage random sample

5.Cluster sample

qouta sampling is

in this method of sampling

qoutas in form of reservation or percentage are established for different classes of population on the bases of age gender nationality etc. a sample is drawn out on the basis of these qoutas

convenience sampling

in this method a researcher simply selects the sample and ssampling units that are easily accessible no extra efforts are taken by the researcher as he simply chooses the samples on the basis of convenience

snowball sampling

this method is used in cases where the population to be studied is rare therefore it is difficult to find good represntative sampling units in this method the researcher initially selects a sampling unit (doctor musician cancer patient depending upon the needs of the study) based on his judgement and then starts taking further samples on the basis of direction advides referral PROVIDED BY THE FIRSST SAMPLING UNIT.

simple random sampling

this method involves the task selecting sampling units randomly out of the sampling frame a researcher may use the following methods for selecting random samples (lottery method random numbers software etc)

stratified sampling

in this method a heterogenous population is divided into different small sub units which are called stratas these stratas are homogenous among themselves with respect to a certain factor or characteristic, items or sampling units are randomly selected from the stratas that together make up the sample

stratas are used in ?

stratified sampling wooooooooooooooooooooooow

heterogenous population divided into small homogenous sub units the unit is called ?

strata

systematic sampling

and how to calculate the k value

in this type of sampling the first unit is selected randomly and then every Kth item on the source list is selected and becomes a part of the sample

K value = total number of units in a population / no of units in the sample

when is cluster sampling is used

when population is veeeeeeeeeery large

cluster sampling

this method is used where the size of the sample is very large

in this method a homogenous population is divided into smaller heterogenous groups and the samples are drawn out at random from these heterogenous groups and these heterogenous groups are called clusters all items belonging to the selected heterogenous groups become the part of the sample

من الاخر ال هومو جروبس دول مشتركين في صفه واحجه كبيره كلهم من الدقهليه مثلا لكن هما بعد كدا اتقسمو ل جروبات اصغر اسمها clusters

والجروبات دي مختلففين عن بعض شويه male شويه female

بلا بلا بلا

لو مش فاهم dm مفتوح : )

in cluster sampling a homogenous population is sub divided into smaller groups named ?

clusters wooooooooooooooow

multi stage sampling

in multi stage sampling the sampling is performed in more than 1 step or stage at first stage units are selected by some random sampling methods usually SRSWOR or systematic sampling and at the second stage again some units are selected out of the previously selected units through some suitable methodss. it can be understood as an expansion of the cluster sampling method where instead of selecting the entire heterogenous group items are drawn randomly from each heterogenous group to form a sample .

صدقني مش لازم تكون حافظها صم اهم حاجه كلامك ايا كان اي حتي لو بالعربي يكون مطابق ل دا ومش منقص منه حاجه فا متقلقش لو مش حافظها صم يعتبر صعب جدا اصلا فا متجهدش نفسك في الفاضضي زي ما انا بعمل لانه كدا كدا مش هيقولك سمعلي او كدا ال

mention 2 random sampling methods used at the first stage of multi stage random sampling

SRSWOR or systematic

احفظ SRSWOR علي كلمه صرصور

اعتبر نفسك بتقول صرصار بس انت سعودي :) :)