Data collection methods have advantages and disadvantages, as shown below. Method


Advantages Direct observations


Surveys / questionnaires


(a) Phone (b) Internet ● ● ● ●


Inexpensive Easy to do


Easily carried out


Questions can be explained ● Many questions can be asked ●


● Experiments Anonymous


● Done in participants own time ●


Accurate data if carried out properly


Interviews


Questions can be explained ● High response rate


● ● Many questions can be asked ● Databases ● ● ●


Inexpensive Fast


Easy to do ●


Inexpensive and easily carried out


Disadvantages


● May include human error ●


Not suitable for all data collection


● ● ● ● ●


Response rate can be low Limited to phone owners Expensive


Limited to people with internet access


Questions cannot be explained ● ● ● ● ● ● Expensive


Time consuming Requires expertise Focused on one task Expensive


Interviewers might infl uence answers


Respondents may not be totally honest


Limited to databases available ● May be out of date


● Collection method unknown


Once the sample size and the method of collection have been decided, the questions to be asked must be designed. Writing good questions is very important to ensure the information gathered is useful.


Guidelines for writing good questions


1. The question should be clear and easily understood by all people. Imagine you want to fi nd out how much TV people watch. You decide to ask: Do you watch a lot of TV? People may interpret ‘a lot’ diff erently.


Yes No


2. It should be possible for everyone to answer the question asked. Imagine you want to fi nd out people’s favourite sport. You decide to ask: What is your favourite sport? Football


Hurling Some people may prefer a diff erent sport. Others may not like any sports.


3. The question should be fair. It should not infl uence a person’s answer. If it does, it is a biased question.


It can be useful to add options such as ‘none of these’ and ‘other’.


Imagine you want to fi nd out people’s opinions on how often students should have PE classes.


You decide to ask: Studies have shown that daily physical activity for children is important. How often should secondary students have PE classes?’ The question provides extra information that might lead a person to answer in a particular way.


Bias is an in-built error that causes the data collected to be inaccurate. It can lead to misleading results.


Section B Moving forward 287


Can you think of a better way to write the example questions?


18 Collecting and representing data


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