Random Sampling : Description
Samples are taken randomly, meaning that every respondent has an equal chance of being sleected.
Generate random numbers to select who to interview using a random number generator
when you know the whole population is available to survey : then use it
Random Sampling : advantages and disadvantages
advantage :
unbiased
can be done with large population size
can be done for large sample size
disadvantage :
may not be representative of the different categories in the whole population
systematic sampling : description
samples are taken at regular intercals : every nth person
sptially, samples are taken at regular intervals
decide on the interval (such as every 5th or 10th person) and select the repondents to do the survey
When you do not know the whole population (i.e. at a public place)
systematic sampling : advantages & disadvantages
advantages : unbiased (but more biased than random sampling) quick to use can be done with large population size can be done for large sample size
disadvantages :
- may not be representative of the different categories in the whole population
- person chosen at the interval might not suitable (for example you need to interview touists, but the 5th person is a local)
stratified sampling : description
samples are taken from specific and distinct groups
- ‘strata’ means ‘layer’ (or sub-groups) of the population, for example, selecting smples from different age groups.
- first, you must divide the population according to the specific and distinct groups
- generate random numbers to select who to interview using a random number generator in each group
when there are subgroups in the population
stratefied sampling : advantages & disadvantages
advantages :
unbiased
able to represent the population better
disadvantages :
very time consuming to conduct
complicated to conduct because it may be difficult to identify the different subgroups
convenience sampling : description
samples are taken at convenience (such as the person standing closest to you, the people who agree to do the survey when you asked, friendly people … etc)
asking anyone that is willing to be surveyed
when sufficient representative people are available to survey
convenience sampling : advantages & disadvantages
advantages :
quick to conduct
disadvantages
biased
may not be representative of the different categories in the whole population
Predestrian / Traffic count : description
- decide which streets you will be conducting the pedestrain/traffic count
- prepare a recording sheet/ tally chart
- choose a safe point to station tyourself, count the number of predestrians/vehicles passing a given point (such as a lamp post) at a given fixed period of time (such as a 10 minute period)
- record the number of pedestrians/vehicles on a tally chart for easy comparisons
predestrian/traffic count : advantages & disadvantages
advantages :
provides a numerical sense of how many people/vehicles are present in the area on a given day. This information can be used to infer human impact on the environment.
disadvantages :
may not be representative of pedestrian/traffic counts across the day/week as the data is collected only at a specific time on a given day.
questionnaire survey : description
- a useful way to obtain the general opinion of a group from a larger pool of people. It should consist of carious types of questions that are crafted to help answer the guiding question of your GI
- start with general questions which are easy to answer (i.e. use closed questions)
- avoid asking leading questions that influence the respondent to anwer in a
certain way.
- avoid asking two questions in one to avoid confusion. - you can ask 1-2 open questions that would require the respondent to elaborate more and provide more personal opinions.
- In general, keep it short and simple to avoid taking up too much of your respondent’s time.
questionnaire survey : advantages & disadvantages
advantages :
- closed questions will allow for easy analysis due to the ease of which you can tabulate results
- open questions allow a more specific point of view
- quick to conduct
- easy to represent the results in a bar graph
disadvantages :
- closed questions do not allow for elaboration of answers. Range of answers may not be sufficient
- open questions can be difficult to tabulate and analyse. Answers may be very specific to the individual
questionnaire : designing
- pay attention to details such as
- length : keep the questionnaire short and quick to complete. try to keep it
within 10 questions - validity : ensure that the questions crafted are based on the hypothesis and
can help you get necessary inforation - layout : try to begin the questionnaire with quick-to-answer closed questions.
you may wish to end with 1-2 open question. - language : use simple and clear language. try not to use geographical terms
that common people may not know. Also, state clearly the instructions, such as
rank, tick or circle, etc. - questions to avoid : senstive qiestions like religion, income and age; questions
that require, a lot of thinking or reflection. An exception is when tht information
is actually required for the investigation
- length : keep the questionnaire short and quick to complete. try to keep it
- decide on sampling method to select repondents before doing the questionnaire
- some guidelines to take note of :
- always inroduce yourself and the purpose of the investgation
- speak politely
- ask for the respondent’s permission before beginning the questionnaire. If declined, thank the person politely anyway
- jot down the responses quickly. do not pass comments or make faces about an answer
- Thank the respondent for his/her time when it is completed
interview : description
- an interview is a conversion between an interviewer and interviewee where questions are asked and answer given. An interview range from structure to unstrcutured.
bipolar survey : description
- a perception survey is a data collection method which is carried out to investigate the views/perceptions. Most often, it is used to investigate the quality of the built environment
- the survey using pairs of opposite statements to descrbe the given criteria. By showing the two extreme ends of each pair, the respondent can then choose the most suitable option
people rank the various criteria such as cleanliness on a scale, that ranges from negative values to positivevalues through 0. - the results are then added up and represented on a bar graph with negative and postive numbers.
interview : advantages & disadvantages
advantages :
- allows for more well-elaborated answers that go beyond the strandardized responses in a questionnaire
disadvantages :
- time0consuming to conduct
- it may also be difficult to get access to people in key postions such as government officials
advantages of open questions :
- allows interviewers to clarify or ask for further elaboration from the interviewees
disadvantages of open questions :
- however it is time-consuming, esp. interviewees have to answer open- ended questions
- not easy to collate or analyse qualitative data
bipolar survey : advantages & disadvantages
advantages :
- quick way to get gauge the perception of the respondents
- respondents can give both positive and negative views on a place
- quick to conduct
- able to represent opinion graphically (as opposed to interviews, which cannot be represented in a graph easily)
disadvantages :
- responses dp not capture the reasons for their choice of the rank
- subjective because it is based on personal opinion
- difficult to derive a conclusion if too many respondents choose the neutral score of 0
landuse survey : description
- this is amapping tool to understand the uses of the land. students shade areas on the map using different colours to identify the type of land use
- for example students might want to shade a map of the mall to categorise the different types of shops
landuse survey : advantages and disadvantages
advantages :
- clear visual representation that categorises land use
disadvantages :
- categorising land use can be subjective to people’s opinions and may not give an accurate representation
- it gives a generic representation of the use of the land. it may not give an accurate representation of multi storey buildings
landuse survey : steps
- on a recording sheet,mark out the main street that you have been assigned
- from the startin point, start walking down and observing the different land uses on the ground floor or the second floor of the shophouses
- walk down the street again, this time sketching on the recording sheet. Use boxes to represent the shops/different land uses along the assigned street. Write the names of the shops/land uses.
- once it is complete, return to refine the map by tidying up the illustrations and categorizing the landuse. Use a legend to represent the different categories. Adding labels or short notes to provide further information about the landuse.
Accuracy
The accuracy of each measurement depends on the quality of the measuring equipment and the skill of the person taking the measurement.
If the equipment is faulty, or the person makes a mistake, the measurement may be inaccurate.
Checking for accuracy :
- did the students do the method correctly
- > such as : did they create the survey from correctly? Did they use the sampling method correctly? Did they do the survey correctly?
Reliability : Description
Can the information be trusted?
Do the results give a good representation of the whole sample?
Generally we can say by increasing the number of time the investigation is carried out or by taking the results at the same time each day/week the more reliable the data becomes.
Reliability : ways to improve
- sufficient quantity :
- > data is collected from enough site
- > enough data is collected (such as enough respondents were surveyed to be representative of the population. Such as 100 respondents)
- standardized : ensure that the investigation is done at the same time every day/week or at the same place every day/week.
