Data Statistics

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