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Research Methodology Dr. Nimit Chowdhary, Professor

Saturday, April 14, 2012 1© Dr. Nimit Chowdhary

How to describe patterns in quantitative data?1. Center2. Spread3. Shape4. Unusual features

Saturday, April 14, 2012 © Dr. Nimit Chowdhary Research Methodology Workshop p. 2

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A histogram is made up of columns plotted on the graph

Frequency

Quantitative variable

Chap 2-4

Presents data in a way that provides substance, statistics and design

Communicates complex ideas with clarity, precision and efficiency

Gives the largest number of ideas in the most efficient manner

Almost always involves several dimensions Tells the truth about the data

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Smith/Davis (c) 2005 Prentice Hall

There are several types of graphs from which the researcher can choose. Your choice of graphs will be determined by which one depicts your results most effectively and by the scale of measurement you used.

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Smith/Davis (c) 2005 Prentice Hall

Pie Chart – depicts the percentage represented by each alternative as a slice of a circular pie; the larger the slice, the greater the percentage.

Smith/Davis (c) 2005 Prentice Hall

Presents data in terms of frequencies per category. A bar diagram is constructed when one is using nominal (or qualitative) categories that cannot be numerically ordered from lowest to highest.

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Smith/Davis (c) 2005 Prentice Hall

Histogram –represents quantitative data in terms of frequencies.

Like the histogram, polygon displays the frequency of each number or score. The only differences between these two graphs are the use of bars in the histogram and the use of connected dots in the frequency polygon.

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In line graphs, there are two axes or dimensions that must be discussed.

One of the variables is plotted on the ordinate and the other is plotted on the abscissa.

How tall should the Y axis be? How long should the X axis be? A good rule of thumb is

for the Y axis to be approximately two thirds as tall as the X axis is long.

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Day Chocolate Strawberry WhiteMonday 53 78 126Tuesday 72 97 87Wednesday 112 73 86Thursday 33 78 143Friday 76 47 162

The cafeteria wanted to collect data on how much milk was sold in 1 week. The table below shows the results. We are going to take this data and display it in 3 different types of graphs.

A bar graph is used to show relationships between groups.

The two items being compared do not need to affect each other.

It's a fast way to show big differences. Notice how easy it is to read a bar graph.

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A circle graph is used to show how a part of something relates to the whole.

This kind of graph is needed to show percentages effectively.

Chocolate Milk Sold

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A line graph is used to show continuing data; how one thing is affected by another.

It's clear to see how things are going by the rises and falls a line graph shows.

Chocolate MIlk Sold

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Chocolate MIlk Sold

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Bar Graph

Line Graph

Circle (Pie) Graph

The same data displayed in 3 different types of graphs.

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Chap 2-18

Using “chart junk” Failing to provide a relative

basis in comparing data between groups

Compressing the vertical axis Providing no zero point on

the vertical axis

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Chap 2-19

Good Presentation

1960: $1.00

1970: $1.60

1980: $3.10

1990: $3.80

Minimum Wage Minimum Wage

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Bad Presentation

Good PresentationA’s received by

students.A’s received by

students.

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FR SO JR SR

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FR = Freshmen, SO = Sophomore, JR = Junior, SR = Senior

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Chap 2-21

Good PresentationQuarterly Sales Quarterly Sales

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Chap 2-22

Good PresentationMonthly Sales

Monthly SalesBad Presentation

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Graphing the first six months of sales.

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