Chapter 13 Flashcards
selection bias
data is not randomly selected sufficiently to represent the population
ie sample = 3% errors
population = 4% errors
selection bias
observer bias
an observer lets their assumptions (may be unconscious) to influence their observations
omitted variable bias
the researcher omits a key variable that results in an incorrect finding
relates to EXPLORATORY DATA ANALYSIS not descriptive analysis
cognitive bias
relates to human perception + how data is presented
self-selection bias
individuals select themselves to be part of a study
confirmation bias
the researcher accepts data that confirms their belief + ignores data that disagrees
survivorship bias
the sample contains data that has previously survived some other event
null hypothesis
if stat sig difference > 95% = reject null hypothesis
descriptive stats
the statistical summarisation of data
inferential stats
the stat findings of a small population of data are taken to be applicable to the characteristics of a larger population
exploratory data analysis
the identification of relationships within a dataset
confirmatory data analysis
using stats to confirm a pre-determined hypothesis
A company correctly records and analyses all its sales transactions. At the end of each month, a
report is produced for the sales director listing details of every sales transaction: customer, products,
quantities and prices. Which of the following describes the quality of the report’s data and
information?
A good quality of data, but poor quality of information
B good quality of both data and information
C poor quality of data, but good quality of information
D poor quality of both data and information
A
Big Dave Ltd collects data about customers and what they buy as well as certain items of personal
information. It analyses this data to identify relationships between the different variables, such as
what products appeal most to people of certain age groups.
Requirement
What type of analysis is this an example of?
A Descriptive statistics
B Exploratory data analysis
C Confirmatory data analysis
D Relativity analysis
B
Which of the following is the best description of professional scepticism?
A All information should be challenged, and should be assumed to be incorrect until it has been
proved otherwise.
B Forecasts that appear optimistic should be ignored, while forecasts that are pessimistic should
be assumed to be correct.
C Assessing the information critically, being alert to possible misstatements due to error and fraud .
D Refusing to accept that information is correct until it has been certified by a qualified accountant.
C
A schools inspector sits in on classes and makes an assessment of the teacher. The teacher is given a
grade from 1 to 5 where 5 is excellent and 1 is inadequate. Without realising that she is doing this,
the inspector tends to give more generous grades to teachers of maths and science, and lower
grades to teachers of arts and humanities. Before becoming an inspector, she was a science teacher.
Requirement
What type of bias is the inspector introducing into her rankings?
A survivorship bias
B cognitive bias
C observer bias
D self-selection bias
C
A data analyst at a major retail chain has performed some analysis in which he has calculated the
mean monthly expenditure, and the average number of visits per month by the chain’s customers.
The information was prepared by using details of credit and debit card payments to enable the
analyst to track all purchases made by a particular customer. Approximately 60% of purchases in the
stores are made using credit and debit cards, and the analyst claims to have tracked the purchases of
10% of card users.
Requirement
In evaluating the statistics produced by the analyst, which of the following conclusion would you
reach?
A Given that 10% of the card users were used in the sample, the statistics are likely to be
representative of the population.
B The data in the sample may suffer from selection bias so it should be recognised that the
statistics may not be an accurate reflection of the whole population.
C Since only a sample of customers was used, the data analysis is likely to be wrong and should
therefore be ignored.
D The data in the sample suffers from omitted variable bias so it should be
B
The directors of a business have asked you to prepare a presentation in which you provide an
overview of the trends in sales over the last 10 years. The company has three main product lines.
Requirement
Which type of chart would be most useful for providing a good overview of the trends in sales over
the last 10 years?
A A clustered bar chart
B A component bar chart
C A pie chart
D A line chart
D
line = best way of identifying trends - good for an overview of sales
Arkwright Ltd analyses huge quantities of data about a wide variety of issues from a wide variety of
sources. Arkwright Ltd is seeking competitive advantage from:
A its transaction processing system
B big data
C cybersecurity
D its strategic process
B - a Co which uses big data for competitive advantage streams in huge quantities from a variety of internal + external sources + applies data analytics to obtain as much value from the data as possible
The ability to stream big data into an organisation’s systems in real time is an example of which
feature of big data?
A Volume
B Veracity
C Velocity
D Variety
C = the speed of data
0 Which of the following features of big data concerns the fact that data sets contain anomalies and
errors?
A Veracity
B Variety
C Volume
D Velocity
A = concerns the trustworthiness or accuracy of data
