Lesson 7: Descriptive statistics

Question 1

What is descriptive data?

Answer 1

Descriptive statistics summarises and describes features of a dataset, like as the range, variation, data distribution and central tendency

Question 2

What are the different types of quantitative measures and give examples

Answer 2

• nominal: eye colour, named
• ordinal: level of satisfaction, named and natural order
• interval: temperature, named, natural order, equal interval between variables
• ratio: height, named, natural order, equal interval between variables, has a ‘true zero’ value thus ratio between values can be calculated

Question 3

why is it important to know what type of data you have?

Answer 3

• can know how to handle different types of data correctly
• what you can calculate with different types
• which describe stats and visualisations are appropriate
• which statistical hypothesis test you can use and cannot use

Question 4

How can qualitative data be altered into quantitative data

Answer 4

ways of measuring qualitative answers can be ‘transformed’ into the number like a written response can be transformed into an ‘intensity score’

Question 5

Are longitudinal or analytical surveys more analytical than descriptive and why

Answer 5

yes as they analyse events at more than one point in time or test a hypothesis so the possibility of suggesting the direction of cause and effect

Question 6

What do analytical surveys do?

Answer 6

collect data that can be statistically compared to analysed for associations/ patterning

Question 7

What are the different types of agreement scales you could use?

Answer 7

• frequency: never, rarely, sometimes
• importance: unimportant, insignificant, important
• liking: dont like at all, like slightly etc

Question 8

What can you calculate using nominal and ordinal measurement scales?

Answer 8

frequency
proportion
percentage
central point

Question 9

How is nominal and ordinal data represented?

Answer 9

• pie charts
• bar charts

Question 10

What can you calculate with interval or ratio data?

Answer 10

• range: minimum and maximum values
• spread: inter-quartile range, SD or confidence intervals
• central point: mean, medium mode

Question 11

definition of SD

Answer 11

measure of how dispersed the data set is from the mean

Question 12

What is one SD of the mean means

Answer 12

68% of the data is wihtin one SD of the mean

Question 13

what does it means when Sd if 1.96

Answer 13

95% of values are within 1.96 Sd of the mean

Question 14

what does it mean when SD is 2.58

Answer 14

99% of the values are within 2.58 Sd of the mean

Question 15

What does it mean when SD is within 3

Answer 15

99.7% of values are within 3 SD of the mean

Question 16

how could interval and ratio data be represented graphically

Answer 16

box plot
histogram

Question 17

how are outliers represented in a box plot

Answer 17

on the sides of the box plot so not included in the box plot