Mean Deviation
Chapter Name : Statistics |
Sub Topic Code : 104_11_15_04_03 |
Topic Name : Mean Deviation |
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Sub Topic Name : Mean Deviation For Grouped Data |
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Introduction
• Statistics deals with data collected for specific purposes. • In order to have better data interpretation we should know how data is scattered and this measure is known as Measure of Dispersion. • Mean deviation for grouped data is a measure of dispersion and it shows the amount of deviation that occurs around mean score of grouped data.
Pre-Requisites:
• Knowledge of representing data graphically and in tabular form. • Knowledge of measure of dispersion. • Knowledge of mean, median of data.
Activity:
You will observe that excel is an easy tool to calculate mean of data.
Real Life Question:
A bank issues credit cards to its customers. Based on past data, it has found that 50% of customers pay on time following the bill. If a sample of 5 accounts is selected randomly from the database. Find absolute mean deviation of accounts paying on time. x : 0 1 2 3 4 f : 1 9 7 3 4
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Statistics | Statistics is a method of gathering, analyzing and making conclusions from data. |
| Grouped data | Data is in groups or intervals like 0-10, 10-20. |
| Mean deviation | Mean deviation of data is the average distance between each data value and mean. |
| Discrete frequency distribution | Given data consist of n different values with frequencies respectively. |
| Continuous frequency distribution | Given data is classified into intervals without any gaps along with their respective frequencies. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Excel spread sheet | Collect data of runs of batsman and enter in excel spread sheet. After the data has been entered place the cursor place the cursor where you wish to have mean of data and click mouse button. Move the cursor to function wizard button and click on it. A statistical dialog box will open select average. |
Real life uses :
Mean deviation of grouped is helpful in data analysis and data interpretation. Data analysis is used in all sciences, business.
Places to visit :
Look for two maximum used commodities in your house and make two data sets. Find absolute mean deviation?
Practical examples around us
| Examples | Explainations |
|---|---|
| Finding polyester decay. | A researcher buried polyester strips in soil for different lengths of time, then dug up the strips and measured force required to break them. Lower strengths means fabric has decayed. He made grouped data on breaking strengths in pounds. The time taken for polyester decay can be found out by taking difference of means of data. |
What you learn in Theory:
Mean deviation is average distance between each data value and mean.
What you learn in Practice:
To get more representative idea about spread of data we use mean deviation. The mean deviation shows the amount of deviation that occurs around a mean score.