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Statistics > Collection Of Data (1) > Flashcards

Collection Of Data (1) Flashcards

1
Q

What is quantatative data

A

Numerical data

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2
Q

What is Qualitative data

A

Non numerical data

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3
Q

What is continuous data

A

Takes a value on a continuous scale (e.g.mass and length - both can be in decimals)

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4
Q

What is discrete data

A

Takes particular (whole number) values on a continuous numerical scale

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5
Q

What is raw data

A

Data that is just as collected - not grouped or rounded

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6
Q

What is categorical data

A

Data which can be sorted into non overlapping catergories

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7
Q

What is ordinal data

A

Data that can be written in order or given a numerical rating scale

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8
Q

What is bivariate data

A

Involving pairs of related data

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9
Q

What is multivariate data

A

Involves sets of three or more related data values

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10
Q

What are class intervals

A

Groups that do not overlap in which data can be grouped.

1-10
11-20
21-30

Intervals do not need to be equal widths, use narrower intervals when the data is close together and wider intervals when the data is spread out

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11
Q

Why do you need to be careful choosing intervals

A

The data trends can be obscured

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12
Q

What are the class intervals like in continuous data

A

The class intervals must not have gaps
Say the interval was 0-5 6-10 where would 5.5 go.

For continuous data use < and <=

E.g

0<t<=10
10<t<= 20

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13
Q

When given a rounded number what are the possible decimals values of that number, between

A

E.g 230

229.5<=x<230.5

A measurement given correct to the nearest whole unit can be inaccurate to 0.5

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14
Q

What is primary data

A

Data collected by or for the person who is going to use it

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15
Q

What is secondary data

A

Data collected by someone else

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16
Q

What is the population

A

Everything / everybody in a group that you are investigating

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17
Q

What is a census

A

A survey / investigation with data taken from every member of a population

(The national census is data taken from every member of the uk)

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18
Q

What is a sample

A

Information about part of a population - to avoid bias it should represent the characteristics of the population

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19
Q

Avantages and disadvantages of primary data

A

Advantages
The collection method is known
Accuracy is known
Can find answers to very specific questions

Disadvanyage

Time consiming to collect
Expensive to collect

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20
Q

Avantages and disadvantages of secondary data

A

Advantages

Easy to obtain
Cheap to obtain
Data from some organisations (e.g office of national statistics) is more reliable

Disadvantages

Method of data collection unknown
Data might be out of date
May contain mistakes
May come from an unreliable source
May be difficult to find answers to specific questions

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21
Q

Advantages and disadvantages of a Census

A

Advantages

Unbiased
Accurate
Takes whole population into account

Disadvantages

Tine-consuming
Expensive
Difficult to ensure the whole population is used
Lots of data to handle

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22
Q

Advantages and disadvantages of a sample

A

Advantages

Cheaper
Less time consuming
Less data to be considered

Disadvantages

Not completely representative
May be biased

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23
Q

What are sampling units

A

The people or items that will be sampled

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24
Q

What is the sampling frames

A

List of all sampling units

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25
Q

What is the Petersen capture recapture formula

A

N=Mn/m

N= the population
M= members of the population tagged / marked
n = new capture size (after time waited)
m= The number that are marked - from that capture size

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26
Q

What is the Petersen capture recapture formula used for

A

Estimating the size of a population

E.g small insect populations that would be impossible to count

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27
Q

What assumptions do we make when using the capture recapture formula

A

The population hasnt changed (no members have left the population or joined)(born/died)

The probability of being caught is equal for all individuals

The marks/tags are not lost and are easily recogniseable

The sample size is large enough to represent the population

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28
Q

What is a random sample

A

A method of sampling where every member of a population has an equal chance of being included

It is unbiased

29
Q

How can we take a random sample

A

Number each piece of data then select the numbered items by:

Using a random number table
Using a random number generator/calculator
Using a computer or apl to generate random numbers
Putting the numbers in a hat and taking them out
Rolling fair sets of 10-sided dice

30
Q

Advantages of random sampling

A

More likely to represent the population (if large enough)
Choice of members of sample is unbiased

31
Q

Disadvantages of random sampling

A

Needs a full list of the whole population
Needs a large sample size

32
Q

What is judgement sampling

A

Use your judgement to select a sample representative of the population

33
Q

What is opportunity sampling

A

Using people or objects available at the time

34
Q

What is cluster sampling

A

Use when data naturally splits into groups
(E.g geographical areas)
The list of clusters is the sampling frame and some clusters are randomly selected from the list to make the sample

35
Q

What is systematic sampling

A

Choose a starting point in your sampling frame at random
Then choose items at regular intervals - e.g every 10th person (after the one you choose)(random number generators can be used to choose your starting position)

36
Q

What is quota sampling

A

Group the population by characteristics
Interview a quota (number) from each group

37
Q

What is stratified sampling

A

Putting the members of each stratum (group) in proportion to the size of that stratum
The sample is selected randomly

E.g
Year. 7. 8. 9. 10. 11
Students 250. 250. 200. 150. 150.

Total students = 1000

Divide each group (strata) by the total then multiply by the sample size you want (e.g 60)

38
Q

What is the explanatory / independent variable

A

The variable that isnt change by others

It is the variable you change

39
Q

What is the response / dependent variable

A

The variable that you are measuring

40
Q

What are extraneous / control variables

A

The variables you control in an experiment

41
Q

What type of experiments are used to collect data

A

Laboratory experiments - conducted in a controlled environment (not necessarily a laboratory).

Field experiments - Experiments carried out in a test subjects everyday environment. A researcher sets up the situation with some control variables

Natural experiments - Carried out in the test subjects everyday environment, the researcher has no control over the variables

42
Q

What are the advantages and disadvantages of laboratory experiments

A

A:
Easy to replicate
You can control extraneous variables

D:
Test subjects may behave differently (in test conditions) to how they would normally

43
Q

What are the advantages and disadvantages of field experiments

A

A:
More likely to reflect real life behaviour

D:
Cant control extraneous variables

44
Q

What are the advantages and disadvantages of natural experiments

A

A:
Most likely to effect real life behaviour

D:
Cant control any variables
Hard to replicate

45
Q

How can you show your data is valid / reliable

A

By repeating it and getting similar data values

46
Q

How can simulation be used

A

It is used to model random real life events, to help predict what could actually happen

It is easier and cheaper than collecting / analysing real data.

47
Q

What is a questionaire

A

A set of questions designed to obtain data

48
Q

What is a respondent

A

The person completing a questionnaire

49
Q

What is an open question

A

A question with no suggested answers

50
Q

What is a closed question

A

A closed question has a set of answers

51
Q

What is one problem with open questions

A

Every respondent could give a different answer making data analysis harder

52
Q

How should you structure a questionnaire

A

Keep answers short with simple language

Avoid biased or leading questions (questions that suggest an answer)

Give intervals that do not overlap (1-10 11-20)

Make sure options cover all possibilities (never / i dont know / 0)
Include a time frame in the question
Avoid questions that will be answered not honestly

53
Q

Advantages and disadvantages of using interviews to collect primary data

A

A:
Interviewers can explain questions.
Interviewers can put people at ease when answering personal questions.
Respondents can explain answers.
High response rate.

D:
May be less honest / less likely to answer personal questions
Can take a long time / more expensive
Smaller sample size
Interviewers may have bias
Respondent may try to impress the interviewer (choose the ‘right’ answers

54
Q

Advantages and disadvantages of using annonymas questionaires to collect primary data

A

A:
Respondents more likely to answer truthfully / answer personal questions.

Questionaire are quick / cheap (all respondents can complete them at the same time)

Easy to send questionairs to a large representative sample

No interviewer bias

D:
Respondents may not understand questions

Researchers may not understand answers

Lower response rate - some people may never answer

55
Q

How can you remove bias from your response rate

A

By using a random response method (uses a random response)

E.g flipping a coin.
If heads answer yes
If tails answer truthfully

The survey results can then be used to calculate an estimate of the proportion who answers yes (when landing on tails)

56
Q

Estimate the proportion of people who have shop lifted

Flip a coin - heads answer yes
Tails - answer truthfully
820 answered yes
730 answered No

A

Find total population
820 + 730 = 1550

Estimate the number of heads (50% chance for heads or tails)

0.5 × 1550 = 775

Estimate for truthful yes answers :
Subtract estimated heads from number who said yes
820-775 = 45

Estimate proportion of people who have shopplifted
(Divide truthfull yes answerd by number who answered truthfully)

45/775 = 0.05808

57
Q

What is a control group

A

This group has no changes to it

E.g give one group treatment and see how they improve, give another group no treatment and see how they improve

58
Q

What is a matched pair

A

Two people from two different groups in your test.
These people have everything in common except the factor being studied

59
Q

What is a hypothesis

A

An idea you test by collecting information and analysing data

60
Q

What 8 factors do you need to consider when planning an investigation

A

Time - how long will the investigation last / take to set up

Cost - how much will it cost to set up / carry out the investigation

Ethical issues - no participant should be harmed / respect peoples rights

Convenience - can you easily get the data locally

How to select your population / sample - identify the population you are interested in

How to deal with non response - how many responses do you need? (Questionnaires send out more than they need back)

How to deal with unexpected results - what do you do about anomalies

61
Q

Advantages / disadvantages of judgement sampling

A

A:
Its cheap and convenient
Requires little planning

D:
May not be representative
Can lead to skewed data
Heavily biased

62
Q

Advantages / disadvantages of quota sampling

A

A:
Cheaper as less respondents are required
Diverse data from multiple groups of a population (e.g different ages)
D:
There can be bias in the selection process

63
Q

Advantages / disadvantages of stratafied sampling

A

A: allows for more accurate unbiased data (you do not select what you are sampling)
Allows you to collect more diverse data (from multiple populations)

D:
The selection of appropriate strata may be complicated
Requires more planning and effort to set up compared to others

64
Q

Advantages / disadvantages of cluster sampling

A

A: significantly easier and more time efficient than other methods

D: an individual cluster (group) tend to have similar ideas, which may cause your answer to be inaccurate or biased

65
Q

Advantages / disadvantages of opportunity sampling

A

A: it is easy and convenient, requiring almost no planning time
Due to its simplicity data can be collected quickly

D:
As you are choosing who to interview there will be a large amount of bias
The sample might not be representative of the population due to the people you are choosing

66
Q

Advantages / disadvantages of systematic sampling

A

A:
Simple and quick
Samples are evenly distributed
Less opportunity for manipulated data

D:
Possibility of unequal selection
Risk of bias
Requires the whole population size

67
Q

What is a pilot study

A

A small scale study, conducted to evaluate the cost-effectiveness, duration and feasibility of your study before starting your full scale research product

68
Q

What are the advantages and disadvantages of a pilot study

A

A:
Helps you resolve any problems in your study, E.g some people may not understand a question

D:
Time consuming, and can be expensive (reduces the amount you can spend on your actual study)

Statistics (8 decks)

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