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By Dr Aijaz Ahmed Sohag
Prep by: Abdul Wasay Baloch
Amna Inayat Medical College
Data
Data
collecting
classifying
Summarizing analyzing
Interpreting numerical data
Variables
Qualitative
Quantitative
Discrete
Continuous
Ordinal
Nominal
Continuous: Blood pressure , height weight
Discontinuous : No of children No of attacks of asthma per week
Qualitative
Categorical
Ordinal
Ordered categories
Grade of breast cancer
Better, same or worst
Disagree, neutral, agree
Nominal
Sex
Alive or dead
Blood group O, A, AB
Qualitative
Countable facts
Discrete
Only frequency changes
Can be expressed in rate ratio
Use Bar, Pie, Picto and spot maps
Test used – chi square, Standard error of proportion
Quantitative
Measureable facts
Continuous
Both frequency and variable changes
Expressed as mean, median and mode
Rest all diagrams, such as histo scatter and other
Test used – ANOVA,Z test and T Tesst
Data Defines as
‘’ collection of observation in scientific way’’
Types
It has two types
Qualitative
Quantitative
Qualitative Data
Qualitative data is categorized as data expressed not in terms of number, e.g. favorite color, height is tall
TYPES:
Normal : when there is not a natural ordringof the categories, e.g. gender, race, religion
Ordinal or Ordered/ Ranked Data: when the categories: when the categories may be ordered, these are called ordinal variable e.g. small, medium, large
NOTE that the distance between these categories is not measured
Used for both qualitative and quantitative
Quantitative Data
Quantitative Data
It is a numerical measurement expressed in terms of numbers
However, not all the numbers are continuous and measureable
E.g. favourite color = 450 nm, height = 1.8m
Discrete
When you just count the numbers e.g 10 pencils
Can not be expressed in decimal
Thought countable, take only whole number values e.g. No of children
Continuous
This is measured on some scale
It has no ends
E.g. counting the pulse rate of class
Measuring BP
Can be measured in decimal
May be measure as fractional values e.g. 17.4C, 162.5 cm etc)
Variables
Characteristic :
Any characteristic whose value is different from one individual to another e.g. height of school boy
A variable is any characteristic which is measured or observed
It is denoted by X
Variables are characteristics associated with the subjects of study e.g. height weight, gender
Variables so called because they tend to vary between subjects
Broadly variables are grouped into quantitative and qualitative variables
Quantitative Variables
Data can be further classified beig qualitative or quantitative
The STATISTICAL ANALYSIS that is appropriate depends on whether the data for variable is qualitative or quantitative
In general, there are more alternatives for statistical analysis when the data are Quantitative
Quantitative Data
Indicate either how many or how much
Always numeric
Ordinary arithmetic operation (e.g. +,- etc) are meaningful only with QULITATIVE DATA