Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Maths As > Stats T1 > Flashcards

Stats T1 Flashcards

1
Q

What happens in random sampling?

A

Every member of the population has an equal chance of being selected. The sample should therefore be representative of the population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does random sampling remove?

A

It removes bias from the sample

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 3 methods of random sampling?

A
  • Simple random sampling
  • Systematic sampling
  • Stratified sampling
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens in simple random sampling?

A

A simple random sample size of n is one where every sample size n has an equal chance of being selected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What do you need to carry out a simple random sample?

A

You need a sampling frame, usually a list of people or things

Each person allocated a unique number & selection of these numbers is chosen at random

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the two methods of choosing numbers in simple random sampling?

A
  • Generating random numbers

- Lottery sampling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is lottery sampling?

A

The members of the sampling frame could be written on tickets & placed into a ‘hat’

The required no. tickets would then be drawn out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens in systematic sampling?

A

The required elements are chosen at regular intervals from an ordered list

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

If a sample size od 20 was required from a population, how would you take the correct sample size?

A

You would take every fifth person

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How must you choose the first person in systematic sampling?

A

They must be chosen at random

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens in stratified sampling?

A

The population is divided into mutually exclusive strata (ie males and females) & a random sample is taken from each

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What should the proportions be like from strata in stratified sampling?

A

The proportion of each strata should be the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the formula used to work out the amount of people we should sample from each stratum?

A

No. in stratum
————————– x overall sample size
No. in population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the advantages of simple random sampling?

A
  • Free of bias
  • Easy & cheap to implement for small populations & small samples
  • Each sampling unit has a known & equal chance of selection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the disadvantages of simple random sampling?

A
  • Not suitable when the population size or the sample size is large
  • A sampling frame is needed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the advantages of systematic sampling?

A
  • Simple and quick to use

- Suitable for large samples & large populations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the disadvantages of systematic sampling?

A
  • Sampling frame is needed

- It can introduce bias if the sampling frame is not random

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the advantages of stratified sampling?

A
  • Sample accurately reflects the population structure

- Guarantees proportional representation of groups within a population

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the disadvantages of stratified sampling?

A
  • Population must be clearly classified into distinct strata

- Selection within each stratum suffers from the same disadvantages as simple random sampling

20
Q

What are the two types of non-random sampling?

A
  • Quota sampling

- Opportunity sampling

21
Q

What is quota sampling?

A

An interviewer/ researcher selects a sample that reflects the characteristics of the whole population

22
Q

How is the population divided in quota sampling?

A

Divided into groups according to a given characteristic

23
Q

What does the size of each group with a certain characteristic in quota sampling determine?

A

The size of each group determines the proportion of the sample that should have that characteristic

24
Q

What is the interviewer’s role in quota sampling?

A

They would meet people, assess their group and then, after interview, allocate them into the appropriate quota

25
Q

What happens if a person refuses to be interviewed in quota sampling?

A

(or if the quota they fit into is full) You simply ignore them and move on to the next person

26
Q

What is opportunity sampling?

A

Consists of taking the sample from people who are available at the time the study is carried out & who fit into the criteria you’re looking for

27
Q

Give an example of people who would be used in opportunity sampling

A

The first 20 people outside a supermarket on a Monday morning who are carrying shopping bags

28
Q

What are the advantages of quota sampling?

A
  • Allows small sample to still be representative of the population
  • No sampling frame required
  • Quick, easy & cheap
  • Allows for easy comparison between different groups in a population
29
Q

What are the disadvantages of quota sampling?

A
  • Non-random can introduce bias
  • Population must be divided into groups - can be costly/inaccurate
  • Increasing scope of study increases number of groups, which adds time and expense
  • Non-responses are not recorded
30
Q

What are the advantages of opportunity sampling?

A
  • Easy

- Cheap

31
Q

What are the disadvantages of opportunity sampling?

A
  • Unlikely to provide a representative sample

- Highly dependant on individual researcher

32
Q

What are the two types of data?

A

Quantitative

Qualitative

33
Q

What is quantitative data?

A

Variable or data associated with numerical observations (aka quantitative variables)

34
Q

What is qualitative data?

A

Variables or data associated with non-numerical observations (aka qualitative variables)

35
Q

Give an example of a quantitative variable

A

Numbered shoe size

36
Q

Give an example of a qualitative variable

A

Hair colour (you can’t give a number to it)

37
Q

What is a continuous variable?

A

A variable that can take any value in a given range

38
Q

Give an example of a continuous variable

A

Time can take any value - eg 2 seconds, 2.1 seconds, 2.01 seconds etc

39
Q

What is a discrete variable?

A

A variable that can take only one specific value in a given range

40
Q

Give an example of a discrete variable

A

The number of girls in a family - because you can’t have 2.56 girls

41
Q

How can large amounts of data be displayed?

A

In a frequency table or as grouped data

42
Q

How is data presented in a grouped frequency table?

A

When data is presented in a grouped frequency table, the specific data values are not shown

43
Q

What are the groups in grouped frequency tables more commonly called?

A

Classes

44
Q

What do class boundaries in grouped frequency tables tell you?

A

They tell you the max and min values that belong in each class

45
Q

What is the midpoint of class boundaries in grouped frequency tables?

A

The average of that class boundary

46
Q

What is the class width in grouped frequency tables?

A

The difference between the upper and lower class boundaries

Maths As (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions