STA301 Short Notes Lectures 1-22

STA301 Short Notes Midterm term · Lec 1 to 22 · Website Link:

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WHAT IS STATISTICS?

Statistics is the science concerned with developing and studying methods for collecting, analyzing, interpreting and presenting empirical data.

Characteristics of Statistics The important characteristics of Statistics are as follows:

Statistics are numerically expressed. It has an aggregate of facts Data are collected in systematic order It should be comparable to each other Data are collected for a planned purpose

Importance of Statistics The important functions of statistics are:

Statistics helps in gathering information about the appropriate quantitative data It depicts the complex data in graphical form, tabular form and in diagrammatic representation to understand it easily It provides the exact description and a better understanding It helps in designing the effective and proper planning of the statistical inquiry in any field It gives valid inferences with the reliability measures about the population parameters from the sample data It helps to understand the variability pattern through the quantitative observations

DATA

The word “data” appears in many contexts and frequently is used in ordinary conversation. Although the word carries something of an aura of scientific mystique, its meaning is quite simple and mundane.

Example In our day to day life, we can collect the following data.

•  Number of females per 1000 males in various states of our country.
•  Production of wheat in the last 10 years in our country.
•  Number of plants in our locality.
•  Rainfall in our city in the last 10 years.
•  Marks obtained by students.

OBSERVATIONS AND VARIABLES

A variable contains all values that measure the same underlying attribute (like height, temperature, duration) across units. An observation contains all values measured on the same unit (like a person, or a day, or a city) across attributes.

QUANTITATIVE AND QUALITATIVE VARIABLES

Quantitative data are data about numeric variables (e.g. how many; how much; or how often). Qualitative data are measures of 'types' and may be represented by a name, symbol, or a number code. Qualitative data are data about categorical variables (e.g. what type).

Discrete and continuous variables

A discrete variable is a variable that takes on distinct, countable values. A continuous variable is a variable that takes on any value within a range, and the number of possible values within that range is infinite.

MEASUREMENT SCALES long

In Statistics, the variables or numbers are defined and categorized using different scales of measurements. The four types of scales are:

•  Nominal Scale.
•  Ordinal Scale.

Nominal Scale A nominal scale is the 1st level of measurement scale in which the numbers serve as “tags” or “labels” to classify or identify the objects. A nominal scale usually deals with the non-numeric variables or the numbers that do not have any value.

Ordinal Scale