Y1 Stats

Question 1

What are the advantages of a census?

Answer 1

Should give a completely accurate result

Question 2

What are the disadvantages of a census?

Answer 2

Time consuming and expensive, hard to process large quantity of data.

Question 3

What is the difference between a census and a sample?

Answer 3

Census measures every member of a population, sample is only from a subset of the population.

Question 4

What are the advantages of a sample?

Answer 4

Less time consuming and expensive, less data to process, fewer have to respond.

Question 5

What are the disadvantages of a sample?

Answer 5

Data may not be accurate, and there may not be enough data to give information about subgroups.

Question 6

When can a census not be used?

Answer 6

If testing the product destroys it.

Question 7

What are the advantages of simple random sampling?

Answer 7

Free of bias, easy and cheap for small populations, each sampling unit has a KNOWN chance of selection.

Question 8

What are the disadvantages of simple random sampling?

Answer 8

Not suitable for a large population as it time consuming / disruptive, needs a sampling frame.

Question 9

What are the advantages of systematic sampling?

Answer 9

Simple and quick, suitable for large populations.

Question 10

What are the disadvantages of systematic sampling?

Answer 10

Need a sampling frame, if the frame isn’t random can introduce bias.

Question 11

What are the advantages of stratified sampling?

Answer 11

Accurately reflects the population structure, guarantees proportional representation of groups.

Question 12

What are the disadvantages of stratified sampling?

Answer 12

Population must be classified into ‘strata’, same as simple random sampling within each strata.

Question 13

What are the advantages of quota sampling?

Answer 13

Allows a small group to represent population,
No sampling frame needed,
Quick, easy and cheap,
Allows for easy comparison between groups

Question 14

What are the disadvantages of quota sampling?

Answer 14

Non-random sampling introduces bias,
Dividing population into groups can be inaccurate,
Hard to scale up,
Non-responses not recorded.

Question 15

What are the advantages of opportunity sampling?

Answer 15

Easy, cheap

Question 16

What are the disadvantages of opportunity sampling?

Answer 16

Unlikely to be representative, and accuracy depends a lot on researcher.

Question 17

What is qualitative data, and what is quantitative data?

Answer 17

Qualitative = non-numerical observations
Quantitative = numerical observations

Question 18

What is continuous data, and what is discrete data?

Answer 18

Continuous can take any value, discrete can only take specific values. Usually integers.

Question 19

LDS - what is cloud cover measured in?

Answer 19

Oktas, eights of the sky covered by cloud

Question 20

Where are the locations in the LDS?

Answer 20

UK: Camborne, Hurn, Heathrow, Leeming, Leuchars
Overseas: Beijing, Perth, Jacksonville

Question 21

Rank the locations in the LDS from most to least far North.

Answer 21

Leuchars, Leeming, Heathrow, Hurn, Camborne, Beijing, Jacksonville, Perth

Question 22

Which location in the LDS is in the southern hemisphere?

Answer 22

ONLY Perth

Question 23

What are sampling frames?

Answer 23

Where individual units of a population are named or numbered.

Question 24

How do you calculate the mean from a frequency table?

Answer 24

The sum of the products of data values and frequencies / sum of frequencies. Easier than it sounds.

Question 25

How do you estimate the location of data through interpolation?

Answer 25

Assume data is evenly distributed within each class. So find width of class then how far along it you are.

Question 26

How are variance and S.D related?

Answer 26

Standard deviation is the root of the variance.

Question 27

How do you calculate variance?

Answer 27

Mean of the squares minus square of the mean

Question 28

On the calc I use, where is the 'frequency' table?

Answer 28

2nd from left, assuming 1-var.

Question 29

How does coding in the form y = (x - a )/ b work?

Answer 29

Mean is (mean of (x) - a )/b S.D is original S.D / b

Question 30

What do you do when finding quartiles?

Answer 30

Use n/4 or 3n/4. If not whole round up, if whole is halfway between that point and the one above it. How weird.

Question 31

Where should the 2nd set of lines be on a box plot?

Answer 31

Either at highest/lowest non-anomalous value OR at the boundary for outliers.

Question 32

What are cumulative freq. graphs useful for?

Answer 32

Finding the quartiles, median etc.

Question 33

What can you comment on when comparing data?

Answer 33

Measure of location, measure of spread.

Question 34

What are mutually exclusive events?

Answer 34

No overlap between events. Events where P(A or B) = P(A) + P(B)

Question 35

What are independent events?

Answer 35

Have no effect on each other. P(A and B) = P(A) x P(B)

Question 36

When can you model something using a binomial dist.?

Answer 36

Fixed number of trials, two possible outcomes, fixed success prob, trials are independent.