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.
