RESS I: Data Anaylsis #1

Question 1

What are the 5 As of practicing EBM?

Answer 1

Ask, Acquire, Apply, Apprais and Assess

Question 2

What is a variable?

Answer 2

A particular characteristic being studied.

Question 3

What is a dataset?

Answer 3

A collection of variables and observations.

Question 4

What is categorical data?

Answer 4

Can only be assigned to a number of distinct categories e.g. sex, blood type.

Question 5

What is numerical data?

Answer 5

Data that can take a numerical values e.g. age, weight

Question 6

How can categorical data be subdivided?

Answer 6

Nominal: No natural ordering e.g. sex or blood type

Ordinal: Data can be ordered e.g. severity or disease stage.

Question 7

How can numerical data be subdivided?

Answer 7

Continuous: Data can take any value e.g. weight.

Discrete: Whole values only e.g. number fo hospital visits.

Question 8

What type of data is:

1. Weight
2. Sex
3. Number of children
4. Symptoms
5. Disease Stage
6. Weight
7. BMI
8. Pain (measured as ‘absent’, ‘mild’ or ‘severe’)

Answer 8

1. Numerical continuous
2. Categorical nominal
3. Numerical discrete
4. Categorical ordinal
5. Categorical ordinal
6. Numerical continuous
7. Numerical continuous
8. Categorical ordinal

Question 9

What is quantitative data?

Answer 9

Numerical data. It is measurable data.

Question 10

What is qualitative data?

Answer 10

Not numerical data

Question 11

How do you graphically present categorical data?

Answer 11

Pie chart, Bar chart, Frequency distribution table

Question 12

How do you graphically represent numerical data?

Answer 12

Histogram, Box and Whisker Plot

Question 13

What are scatterplots used for?

Answer 13

To display relationships between numerical data (using tow continuous variables).

Question 14

What does positively screw data look like on a histogram?

Answer 14

The bell-shaped distribution is shifted heavily to the right. Thinner ends are called tails
If one tail stretches out farther than the other, the histogram is skewed.

Question 15

What does negatively screw data look like on a histogram?

Answer 15

The bell-shaped distribution is shifted heavily to the left. Thinner ends are called tails
If one tail stretches out farther than the other, the histogram is skewed.

Question 16

What is the normal distribution?

Answer 16

A bell-shaped distribution that is symmetrical.

Question 17

What is the explanatory variable?

Answer 17

The independent variable

Question 18

What is the outcome variable?

Answer 18

The dependent variable

Question 19

What type of descriptive statistics doe you use on categorical data?

Answer 19

Frequency, Proportion and Percentages

Question 20

What type of descriptive statistics doe you use on numerical data?

Answer 20

Mode, Median, Range (and IQR), Standard Deviation

Question 21

What is mean?

Answer 21

The average value. This is calculated by adding up the sum of the values and dividing this value by the total number of values.

Question 22

What is the median?

Answer 22

Where the mid-point of the measurement values lies.
Defined as the value above and below which, half (50%) of the measurements lie.

To calculate the median:

1. Sort observations in numerical order
2. Find the mid point
3. If two values lie at the mid point, average them

Question 23

What is the mode?

Answer 23

The most common value.

Question 24

What is the range?

Answer 24

The difference between the highest and lowest data value. This indicates the extreme within which all measurements lie.

Question 25

What is standard deviation?

Answer 25

Summarises the average speed of values around the mean. The larger the standard deviation, the further away the values are, on average, from the mean i.e. the more spread out are the values

Question 26

How do you calculate the standard deviation?

Answer 26

1. Calculate the mean 2. Subtract the mean from every value 3. Square these new values, and add up 4. Divide this total by (n-1) = variance 5. Take the square root = standard deviation

Question 27

How do you calculate interquartile range?

Answer 27

1, Order the data 2. Divide into two halves using the median (exclude median) 3. Lower quartile = median of lower half 4. Upper quartile = median of upper half This shows the spread of values around the median.

Question 28

What measures do you use for normal distributed data?

Answer 28

Mean and standard deviation | can also use mode and range

Question 29

What measures do you use for skewed data?

Answer 29

Median and interquartile range | can also use mode and range

Question 30

What are Box and Whisker Plots?

Answer 30

Box-plots are graphical representations of the average, spread and extreme values. They display the median, inter-quartile range and range. They can be used for data which are skewed (or not). If data are normally distributed, median is approximately equal to the mean.