Descriptive Statistics

Question 1

What are descriptive statistics?

Answer 1

they described the data shown as a number which summarises the observed data
only tells us about sample

Question 2

What are the 2 types of descriptive statistics

Answer 2

measure of central tendency
measures of dispersion (or spread)

Question 3

What are the measures of central tendency?

Answer 3

mean, median, mode

Question 4

what is a strength of the mode?

Answer 4

easy to calculate and not distorted by extreme values

Question 5

what is a weakness of the mode?

Answer 5

focuses only on one value

Question 6

what is a strength of the median?

Answer 6

less affected by outliers

Question 7

what is a weakness of the median?

Answer 7

only uses 1-2 data points so doesn’t take into account all the data

Question 8

what is a strength of the mean?

Answer 8

good representation of the data set due to taking all values into account

Question 9

what is a weakness of the mean?

Answer 9

affected by extreme values, not useful for nominal data

Question 10

What data level is linked to the mode?

Answer 10

nominal data

Question 11

what data level is linked to the median?

Answer 11

ordinal

Question 12

what data level is linked to the mean?

Answer 12

interval

Question 13

what are the measures of dispersion?

Answer 13

range, interquartile range, variance, standard deviation

Question 14

what is the range?

Answer 14

differences between the highest and lowest variable

Question 15

what is the IQR?

Answer 15

you remove the upper an lower 25% of data, then complete the range in the middle 50% of scores

Question 16

What is variance?

Answer 16

measure of how much values in a data set differ from the mean

Question 17

How do you calculate variance?

Answer 17

find mean of data
find difference between each value and the mean
square each difference
add up squared differences
divide sum of squared differences by no. of data points

Question 18

what is S.D?

Answer 18

square root of variance

Question 19

Strengths and Weaknesses of range

Answer 19

+ easy to calculate
- effected by extreme values
- doesn’t take into account all data values

Question 20

strengths and weaknesses of IQR

Answer 20

+ less effected by extreme values
+ good for ordinal data
- doesn’t use all the data values

Question 21

strengths and weaknesses of S.D

Answer 21

+ scale invariance
+ uses all the scores
- time consuming to conduct

Question 22

strengths and weaknesses of variance

Answer 22

+ treats all deviations the same
- sample size

Question 23

normal distribution

Answer 23

symmetric, few extreme scores on each end, bell shaped curve
mean, median and mode close together

Question 24

Skewed distributions

Answer 24

majority of scores on one end
extreme scores affect mean

Question 25

Positively skewed distribution

Answer 25

data extends to right side
most data clustered on left
mode, median then mean extends off

Question 26

Negatively skewed distribution

Answer 26

data extends to the left side of the most data clustered on the right
mean, median, then mode (right side)

Question 27

What descriptive statistic would you use for interval/ratio data with a skewed distribution?

Answer 27

median
range

Question 28

what descriptive statistic would you use for interval/ratio data with a normal distribution?

Answer 28

mean
standard deviation