COLLECTING and REPRESENTING DATA Flashcards
What are the two types of data
Quantitative and Qualitative
What are the two types of Quantitative data?
Continuous and Discrete data
Define qualitative data
non-numerical data such as type of car or colour of hair.
Define quantitative data
numerical data such as measures of height or weight
Define categorical data
Variables can be sorted into categories. Categorical
data is always qualitative.
What is Bivariate data?
Bivariate data involves pairs of related data values, such as exam results and time spent
on study.
What is multivariate data?
Multivariate data involves sets of three or more related data values, such as
age, height and weight.
What is Primary data?
Primary data is information that you collect
yourself.
You could do an experiment, carry out a survey
or use a questionnaire to collect primary data.
What is Secondary data
Secondary data comes from published sources,
such as newspapers, books or the internet.
You could take information from a table in a
magazine to collect secondary data.
Sylvie wants to investigate whether a new type of medication helps people who have difficulty sleeping. She plans to run a laboratory experiment in a hospital with patients who suffer from
this condition.
Identify the explanatory and response variables in this experiment.
The explanatory variable is the type of medication.
The response variable is the degree of difficulty the patient has in sleeping.
what is an outlier or anomalous value?
Values that does not fit the pattern of the rest of the data.
Sylvie wants to investigate whether a new type of medication helps people who have difficulty sleeping. She plans to run a laboratory experiment in a hospital with patients who suffer from
this condition.
Describe one advantage and one disadvantage of doing this as a laboratory experiment.
An advantage is the medication can be controlled and the amount of sleep can
be measured.
A disadvantage is that the patient may experience difficulty in sleeping because they
are out of their home environment.
Define population
A population is everything or everybody
that could possibly be involved in an
investigation, e.g. students in a school, all
the people who use the local gym.
Define census
A census gathers data from the whole
population.
Define sample
A sample gathers data from some of the
population.
Define representative sample
A representative sample should contain
all the characteristics of the population to
avoid bias. A sample that is too small may
not represent the population and may bias
the results.
Define sampling units
The sampling units are the people or items
that are to be sampled.
Define Sampling frame
A sampling frame is a list of all the
members of the population from which the
sample will be taken.
Define pilot survey
A pilot survey is a small sample analysed
first before any large-scale samples.
Define pre-test
A pre-test is a pilot where questions for a
questionnaire are usually tried out.
Define random sample
A random sample is one in which every member of the population has an equal chance of
being selected.
What are the methods for random sampling?
Give each item in your sampling frame a unique number. To select the numbers for the items
in your sample, you can:
* use a random number table
* use a random number generator on a computer or calculator
* put the numbers of the items on pieces of paper and select at random from a hat
* roll sets of fair 10-sided dice to generate digits from 0 to 9.
Advantages of random sampling
Random sample is more likely to be
representative of the population, provided
the sample is large enough.
Choice of members of sample is unbiased.
Disadvantages of random sampling
A full list of the whole population is needed.
A large sample size is needed.
Define stratified sampling
Stratified sampling can be used when the population can be split into distinct groups.
What is a strata/stratum?
A stratum is a group in the population.
In a stratified sample, the relative sizes of the groups in the sample are the same as their relative sizes in the whole population.
What is the formula to work the number of sample in each strata?
(stratum size/population size) x number in sample
Define Judgement sampling
Judgement sampling uses judgement to select a sample that is representative of
the population.
Define Opportunity sampling
Opportunity sampling uses the people (or objects) that are available at the time.
Define Cluster sampling
Cluster sampling can be used when the population is in groups. A random sample
of these groups is selected and all items in the selected groups are included in
the sample.
Define Quota sampling
Quota sampling involves splitting the population into groups with certain
characteristics (e.g. age, gender) and selecting a given number from each group.
For example, a market researcher might ask 10 adults and 10 children about their reaction to the 2018 GCSE results.
Define Systematic sampling
In systematic sampling, items are selected from the population at regular intervals either in time or in space. For example, every 5th car that passes a location or every 3rd house on a street.
What is a questionnaire?
A questionnaire is a set of questions designed to collect primary data.
What are the advantages of questionnaire?
- Much cheaper to do
- Each person answering the question is
treated in the same way
What are the disadvantages of questionnaire?
- Can be inflexible
- People may misunderstand
some questions
What are the golden rules for designing a questionnaire? Hint: There are five golden rules
✓ Make questions clear and closed.
✓ Avoid open questions.
✓ Don’t ask leading questions.
✓ Have response boxes which are
unambiguous.
✓ Have response boxes which cover all
possible replies and don’t overlap.
What is a hypothesis?
A hypothesis is a precise statement about something you can measure that can be tested by collecting and analysing data.
Rosa wants to investigate the amount of time
male and female students spend using their
mobile phones each day.
(a) Write a hypothesis Rosa could use.
Female students spend more time on their mobile phones than male students.
What is a Choropleth map?
A choropleth map uses different colours or shading to show how data varies across different geographic areas.
What are the three types of Skewness?
Positive Skew: Most of the data values are at the
lower end and the distribution is
stretched out in the positive
direction.
Symmetrical: The distribution is symmetrical about the middle and has no skew.
Negative Skew: Most of the data values are at the
upper end and the distribution is stretched out in the negative
direction
What are the things to watch for in misleading diagrams?
- vertical scales that are too big or too small, are not linear or do not start at zero
- axes that are not labelled clearly
- missing features, such as a key
- 3D diagrams, which may distort the features.
