Statistics

Lecture-Chapter 1

1. Statistics is defined as an art and science of (i) Collection of data, (ii) analyzing data and (iii) Interpreting data.

2. Data: Data consists of information coming from observations, counts, measurements, or responses.

Example: Age of the patients who come to the Hospital. Age is also called a variable as it changes from patient to patient.

How many variables are there in the hospital data? The data are information for each variable.

3. Population: A population is the collection of all outcomes, responses, measurements. For Hospital data, if we consider the ages of the patients, then all patient’s ages for all years of its services constitute the population of ages of patients. Similarly, the other data for all years of service will constitute populations.

4. Sample: A sample is a subset of population. For hospital data, the ages of the patients for one year (from October 2002 to September 2003) will constitute a sample.

5. Parameter: A Parameter is a characteristic of a Population. The average value of the age in the population usually denoted by µ (for mean) is a parameter.

6. Statistic: A Statistic is a characteristic of a sample. Such as the average age of the patients in a sample of patients from the population.

Data

Elements Variables Observations

Types of Data: Level of Measurements Qualitative Data: Quantitative data

Qualitative data consists of attributes, labels or non numerical entries

Quantitative data consists of numerical measurements or counts.

Example:

In the Hospital data: the variables are: Gender, Age, Stay overnight, number of visits, Amount of time, Amount of money, type of ailment.

Qualitative data are Gender, Stay overnight, type of ailment.

Quantitative data are Age, number of visits, Amount of time, amount of money.

Level of measurements:

Nominal level of measurements:

Names, labels, qualities

Gender, Ailments, Stay overnight.

Ordinal level of...