Topic 2 (statistics)

Question 1

Central tendency

Answer 1

Averages
mode
median
mean

Question 2

Mode

Answer 2

Value in class that occurs most often

Question 3

Median

Answer 3

Q2
The middle value when data values are in order
N divided by 2 = whole number = find midpoint of corresponding term and the term above
N divided by 2 = not a whole number = round number up and chose that corresponding term

Question 4

Mean

Answer 4

Sum of all values divided by the number values

Swiggly Z = sum of
-x x bar is the mean if the population
X bar = sum of x divided by n

Question 5

Pros and cons of mode

Answer 5

Pros 
Used with non numerical data and numerical (qualitative/quantitative)
Not skewed by outliers and anomalies 
Always an actual data value 
Used for single mode or bi-modal data 

Cons
Sometimes no mode or multiple modes
Doesn’t consider every data point

Question 6

Pros and cons of median

Answer 6

Pros
Not skewed by extreme values
Unaffected by an anomaly or outlier

Cons
Not always being a data value
Doesn’t use every value in data set

Question 7

Pros and cons of mean

Answer 7

Pros
Considers all the data values

Cons
Can be skewed by extreme values
Affected by anomalies

Question 8

Lower quartile

Answer 8

Q1 25%

N divided by 4

Question 9

Upper quartile

Answer 9

Q3 75%

3n divided by 4

Question 10

Decile and percentile

Answer 10

Decile - splits data in tenths - D

Percentile - splits data into hundredths - P

Question 11

3 averages

Answer 11

Mean
Mode
Media

Question 12

4 measures of spread

Answer 12

Range
IQR
VARIANCE
STANDARD DEVIATION

Question 13

median raw data & data has been grouped

Answer 13

list of data:

• no observations in ordered list find n divided by 2
• if whole no = find midpoint of that term and term above
• if not whole no = round number up and chose term

unknown data points:
-no observations in ordered list find n divided by 2 = approximate position of mean

Question 14

lower quartile and upper quartile raw data & data has been grouped

Answer 14

list of data(raw)

• no observations in ordered list find n divided by 4 (LQ) or n x3 divided by 4 (UQ)
• if whole no =find midpoint of that term and term above
• if not whole no = round number up and chose that term

unknown data points:
-no observations in ordered list find n divided by 4 =
approximate position of lower/upper quartile

Question 15

linear interpolation

Answer 15

assumption all the points in a class are spread in a linear way ( find where the median/UQ/LQ lies in a class) 
-gives you an actual value using all data points

Question 16

measures of dispersion

Answer 16

how spread out the data is (consistency)

Question 17

range and IQR +ves and -ves

Answer 17

Range:
positives doesnt exclude extreme values
negatives includes extreme values and can be skewed

IQR:
positives: excludes extreme values
negatives doesnt include all data

Question 18

standard deviation

Answer 18

mean of the squares mines the squares of the means
average distance from the mean
(formula in formula book )

Question 19

coded data implications

Answer 19

when add or subtract = standard deviation stays same and also applies to range or IQR

add or subtract = affects median/mean and mode

multiply or divided affects all of them including variance