Descriptive Statistics

Descriptive statistics is a branch of statistics that is used and also focuses on summarizing and organizing data to make it easily interpretable. It involves different measures that each describes the data like measures of central tendency, measures of dispersion and measures of frequency distribution. Some key takeaways are: 
 

• Descriptive statistics summarizes or describes the characteristics of a dataset.
   
• Descriptive statistics consists of three basic categories of measurements: measures of variability, measures of central tendency and measures of frequency distributions.
   
• Measures of central tendency include mean, median, and mode.
   
• Measures of variability include range, variance, standard deviation.
   
• Measures of frequency distribution include the occurrence of data, frequency counts, class intervals.

There are many types of descriptive statistics. Descriptive statistics can be categorized into three types:

• Measures of Central Tendency
   
• Measures of Variability
   
• Measures of Frequency Distribution
   

Let us now understand the types of descriptive statistics:

Measures of Central Tendency: 

We use the measures of central tendency to describe the center or average of a data set. The types of measures that are used to measure the central tendency is:

• Mean: Mean is the average of all the values in the data set. We calculate the mean by adding up all the values and dividing the result by the number of observations

• Median: Median is the middle value of an ordered data set. We calculate the median by finding the middle value of the dataset if the dataset is odd. If the dataset is even, then we average the middle values to get the median.

• Mode: Mode is the most frequently occurring number in a dataset.

Measures of Variability:

We use different measures of variability to show how the data is spread or distributed. To check the spread or distribution of data, we use the following measures:

• Range: Range is the difference between the highest and lowest points in a given distribution.

• Variance: Variance measures how the data points differ from the mean.

• Standard Deviation: Standard deviation measures the dispersion or spread of data points around the mean in the dataset.

• Interquartile Range (IQR): IQR is the difference between the third quartile and the first quartile, showing the spread of the middle 50% of data.

Measures of Frequency Distribution: 

A Frequency Distribution Table helps summarize how data points are distributed across categories. The frequency table includes measures like:

Data Intervals: Data intervals, also known as classes or categories, are based on the range. This is useful for large datasets or continuous data.

Frequency Counts: The frequency counts, or “f,” is the number of times a data value appears in a dataset. It helps us in understanding how common or rare certain values are.

Relative Frequency: The relative frequency is a proportion of the occurrences of a particular class relative to the total number of observations.

Cumulative Frequency: It is the running total of frequencies up to a certain class interval. 

There are a lot of differences between descriptive and inferential statistics. Let us now see the differences of descriptive statistics and inferential statistics in the given table mentioned below:

There are various ways to represent descriptive statistics. Some of the ways are mentioned below:

• Numerical Representation:

• We use this method as it provides key measures to summarize data like mean, median, and mode. It also uses measures of dispersion like range, variance, and standard deviation. Descriptive data uses measures of position like percentiles and quartiles and z-scores.

• Tabular Representation: 

•  This type of representation is used to organize and summarize data for easy interpretation. We use the frequency distribution table, the grouped frequency table and the cumulative frequency table to represent the organized form of data.

• Graphical Representation: 

• We use this type of representation to visualize the data and help us in finding patterns and trends. Some types of graphs used are bar charts, histograms, pie charts, box plots, scatter plots and line graphs.