STATISTICS

INTRODUCTION1.The word “statistics” is used in both its singular and plural form.

2.In singular sense it is the science of collection, presentation, analysis, and interpretation of numerical data.

3.In plural sense it means numerical facts or observations collected with definite purposes.

4. For example, expenditure and income of persons in a particular locality are statistics.

1.Statistics are expressed quantitavely and not qualitatively.

2.A single observation doesn't form statistics. It is a sum of total observation.

3.Statistics are collected with a definite purpose.

4.Statistics in an experiment are comparable and can be classified into various groups.

STATISTICAL DATA

The word data means information. Statistical data’s are of two types 1.PRIMARY DATA 2.SECONDARY DATA.

Primary Data- When an investigator collects data himself with a definite plan or design in his/her mind it is primary data.For example- data in a population census.

Secondary Data- Data which are not originally collected rather obtained from published or unpublished sources are secondary data.For example- literature reviews, case studies.

FREQUENCY DISTRIBUTION

Frequency distribution is a method to present raw data in the form which one can easily understand the information contained in the raw data.

Discrete Frequency Table- It is constructed from the given data by the use of the method of tally marks.

Grouped Frequency Table- A frequency distribution is table that categorizes scores by intervals.

Grouped Frequency Table

Discrete Frequency Table

STATISTICAL GRAPHSOne goal of statistics is to present data in a meaningful way. It's one thing to see a list of data on a page, it's another to understand the trends and details of the data.

1.BAR GRAPHS- It is a pictorial representation of the numerical data by a number of rectangular bars of uniform width erected vertically or horizontally with equal spacing between them.

Each bar represents one numerical data.

The height and length of bars are corresponding to the numerical data.

title

Data on y- axis

Data on x- axis

bar

scale

HISTOGRAM-1.A histogram is a representation of frequency distribution in the form of rectangles.2.A histogram is made with the help of class intervals.3.Bases and heights are corresponding to frequencies. There is no gap between two rectangles.

Data on y- axis

title

Data on x- axis

bar

scale

FREQUENCY POLYGON-1. A frequency polygon shows a frequency distribution emphasizing the overall pattern in the data.2. It is constructed from a histogram.  The frequency polygon is a polygon - a closed two-dimensional figure of straight line segments - joining the mid points of the top of the bars histogm. title

Data on y- axis scale

Data on x- axis

MEAN, MODE AND MEDIAN

MEDIAN- Median of a distribution is the value of the variable which divides the distribution into two equal parts.

In other ways it is the middle most value.

If ‘n’is an odd number then the value of median= (n+1)/2

If ‘n’ is an even number then the value of median=  [(n/2) or (n/2 +1)

MODE-It is the most frequently occurring observation.

MEAN-It is simply the average of all the observations.

It is calculated by adding all the values of observation and dividing it by the total number of observations.

x = {x1+x2……….xn/} No. of observations

THANK YOUMADE BY : AKSHIT GOEL

AND RISHABH GARG