Data Sources

Chapter 1

Introduction

• This presentation covers the following:

– Primary and Secondary sources of information

– Advantages and Disadvantages of using different sources of information

– Static and Dynamic sources of information

– Quality of data

Data Source

• Data doesn’t magically appear. Someone must have collected it.

• Likewise, information comes from data and what we do with it.

• Where we get the data from is known as the source.

Primary (Direct)

• This is data collected from it’s original source.

• Think of it as data which has been physically collected by you.

Secondary (Indirect)

• Secondary data can come in two ways:– Collecting data for one reason and then using the same data for

another reason. For example, collecting data about plane tickets to make sure they aren’t over booked, and then using the same data to find out which destination was the most popular.

– Other organisations/people may collect data and you can then use the data which they have collected.

Primary vs Secondary• Primary:– Advantages:

• You can control how the data is collected• You can specify the data which is to be collected• You can be more dynamic with your data collected based on

previously recorded data entries.

– Disadvantages:• If you need data you need to get it yourself – this can take

time.• The amount of data you can collect could be small compared

to a secondary source.

Primary vs Secondary• Secondary:– Advantages:

• Can get a large range of data• Can get data from a range of providers/sources• Can get data immediately if it has already been collected• Some analysis may have already been carried out on the data

– Disadvantages:• May not be able to tell if it is biased or not?• You can’t be sure if the data is accurate• You may not have all the facts about how it was collected which

means it might not be suitable for your need• You might have to pay for the information

Take note:• Describe the difference between primary and secondary

sources giving an example for each one using the context of a pet food company.

• Describe two advantages of using an original source to collect information on how good different MP3 players are.

• Give two examples where by using indirect sources are more suitable than using direct sources. For each situation explain why.

• Describe one situation where it would be advantageous to use both direct and indirect sources of information.

Static and Dynamic

• Static:– Once created does not change

• Dynamic:– Once created it can be modified and updated.

Static

• Think of static information sources as a hard copy.

• Information in a book can not be updated unless a new book is released.

Dynamic

• Web pages are excellent examples of dynamic data sources.

• Some websites refresh automatically with new content all the time.

• BBC Sports has ‘As it happens’ updates which show what is happening in an event.

Take note:• What is the difference between static and dynamic

sources of information?

• Give two reasons why websites are classified as dynamic sources of information.

• Give two examples where static sources would be preferable to dynamic sources.

• What problems could you face when using dynamic sources? Give two examples.

Take note:

• Create a two column table which compares CD-ROMs and Websites as sources of information.

• Use this table to help you out:CD-ROM Websites

There is a limited amount of information available.

The WWW provides large quantities of information.

Does not require internet access. Only people with internet access can access the information.

Data cannot be updated quickly. Updates can happen within seconds of new data being received.

... ...

Quality of information

• GIGO:– Garbage In Garbage Out

• If you enter incorrect data into a computer it will return inaccurate results.

Quality factors

• There are six factors that determine how good data is (depending on the situation):

– Accuracy– Relevance– Age– Completeness– Presentation– Level of detail

Take note:

• Describe each of the six factors affecting the quality of the information.

• For each factor, give an example of how it affects the quality of the information produced.

• Demonstrate, using examples, how one factor can have a knock-on effect and influence other factors.