Summarizing Data

Question 1

Definition of quantitative

Answer 1

Anything that can be measured

Question 2

Definition of continuous

Answer 2

Any value valid between a range

Question 3

Definition of discrete

Answer 3

Data can only take certain values

Normally integers

Question 4

Definition of categorical

Answer 4

Individuals fall into different groups

Question 5

Definition of dichotomous/binary

Answer 5

2 categories

Question 6

Definition of ordered

Answer 6

+2 categories which are related

Question 7

Definition of unordered/nominal

Answer 7

+2 categories which are unrelated

Question 8

Why summaries data

Answer 8

Monitor data quality
Check for invalid/missing entries
Describe characteristics of participants in a study
Before a complex analysis

Question 9

What are the 2 types of quantitative data

Answer 9

Continuous

Discrete

Question 10

What are the 3 types of categorical data

Answer 10

Dichotomous
Ordered
Unordered/nominal

Can reclassify quantitative data into categories for ease of reporting

Question 11

What are the 2 ways of summarizing continuous data

Center of data

Answer 11

Mean

Median

Question 12

What are the 4 ways of summarizing continuous data

Spread of data

Answer 12

Range
SD
Variance (SD^2)
IQR (used if data skewed)

Question 13

What is the formula for SD

Answer 13

√(∑(x-x)^2)/n-1 = SD

Question 14

How would you summarize categorical nominal data

Answer 14

Frequencies in each category
Proportion or %
Avoid excess use of DP

Question 15

How would you summarize categorical ordinal data

Answer 15

Frequencies in each categories
Proportion or %
Cumulative proportion/%

Question 16

What are the 2 graphical ways of displaying continuous data

Answer 16

Histograms

Box plots

Question 17

How do you interpret histograms for continuous data

Answer 17

Shape of distribution =range, middle

Areas in rectangles = proportional to no in category

Question 18

How do you interpret box plots

Answer 18

Median = horizontal line in box
UQ = top edge of box
LQ = lower edge of box
Max = top of whisker
Min = bottom of whisker
. = outliers

Question 19

Describe the 3 shapes of distribution

Answer 19

Symmetric
+ve skew
-ve skew (less common)

Question 20

Describe the percentages associated with SDs

Answer 20

1SD = 68% of data within +- 1SD
2SD = 95% of data within +- 2SD

Question 21

Why are bar charts used

Answer 21

Quicker to understand than a table

Shows frequency or % in each category

Question 22

Why are pie charts used

Why are they not ideal

Answer 22

Size of slice = frequency
Popular but bar charts and tables preferred
Hard to compare size of slices