PAS 1

Question 1

What do line graphs imply?

Answer 1

that it is reasonable to interpolate between any observed readings

Question 2

What should you look at first when inspecting and plotting data, before calculating statistics?

Answer 2

RAW DATA

• look at the actual numbers
• check for obvious mistakes and impossible observations
• graph and results and look at them

Question 3

Summary statistics

Answer 3

statistics that summarise your data

Question 4

The disadvantage and advantage of using summary statistics

the exception to the disadvantage

Answer 4

You lose information by doing this, but you gain a greater understanding of the overall picture/trends in the data.

the exception to the disadvantage - dot plots retain all the data in its original form

Question 5

Measures of Average/central tendency

Answer 5

Mean- common average

Median- middle value

Mode - occurs the most frequently (2 = bimodal)

Question 6

Measures of Spread

Answer 6

Range- smallest to largest value

Standard Deviation- measure of spread of data around the mean

Variance- average of the squared difference from the mean, or the square of the standard deviation

Interquartile Range- covers middle two groups

Question 7

The disadvantage and advantage of using interquartile range

Answer 7

it is not useful with small numbers of observations

help rule out extreme values or outliers in the data

Question 8

the disadvantage of the mean and range

Answer 8

outliers/extreme values can affect the mean and range

Question 9

Types of Data

Answer 9

Numerical (quantitative) Data

Categorical (qualitative) Data (e.g. male/female)

Question 10

Continuous (numerical) data

Discrete (numerical) data

Answer 10

can take on any real-number value within some range

can only take specific value

Question 11

Nominal, ordinal and dichotomous data

Answer 11

1. NOMINAL - no natural order to the categories e.g. hair colour or degree of course
2. ORDINAL- there is a natural order to the categories e.g. months of the year, satisfaction scale from 1-10
3. DICHOTOMOUS - there are only 2 options e.g. yes/no vote, leave/remain vote

Question 12

the disadvantage of the standard variation

Answer 12

large outliers will create a higher dispersion

Question 13

What are the means of variance

Answer 13

variation - an average of how much each number in a group of numbers differs from the group mean.

mean deviation - a measure of how closely grouped your data values are.

standard deviation - the measure of the average distance our observations are from the mean.

Question 14

how do you calculate mean deviation

Answer 14

1. calculate the mean
2. calculate the deviation of each value from the mean
3. drop the negative sign
4. find the mean of the deviations

Question 15

how do you calculate standard deviation

Answer 15

1. 1. calculate the mean
2. calculate the deviation of each value from the mean
3. square each deviation
4. sum of the squared deviation
5. divide by n-1
6. square root