eM3 – Displaying data

Question 1

X = Categorical
Y = Counted quantitative

Answer 1

Pie chart

Question 2

X = Categorical/counted quantitative
Y = Quantitative

Answer 2

Bar chart

Question 3

X = Continuous quantitative
Y = Quantitative counted

Answer 3

Histogram

Question 4

X = Categorical
Y = Continuous quantitative

Answer 4

Dot plot / Box and whisker

Question 5

X = Continuous quantitative
Y = Continous quantitative

Answer 5

Scatter plot

Question 6

When would you use a pie chart?

Answer 6

X = Categorical
Y = Counted quantitative

Question 7

When would you use a bar chart?

Answer 7

X = Categorical/counted quantitative
Y = Quantitative

Question 8

When would you use a histogram?

Answer 8

X = Continuous quantitative
Y = Quantitative counted

Question 9

When would you use a dot plot?

Answer 9

X = Categorical
Y = Continuous quantitative

Difference to the bar chart because shows the distribution of data best for small amount of data

Question 10

When would you use a box and whisker diagram?

Answer 10

X = Categorical
Y = Continuous quantitative

Question 11

When would you use a scatter plot?

Answer 11

X = Continuous quantitative
Y = Continous quantitative

show similarities

Question 12

What does box and scatter plot represent and show?

Answer 12

1. lower extreme
2. lower quartile
3. median
4. upper quartile
5. upper extreme

interquartile range
whisquers show= extremities

But they are used more for non parametric data

Question 13

What are the line graphs used for?

Answer 13

Line graph: a diagram showing a line that joins several points and more often used to show the impact of time on a dependent variable. An advanced form of a line graph is a Kaplan-Mieir graph that is used for survival analysis.

Question 14

What are the Cumulative frequency curve used for?

Answer 14

Cumulative frequency curve: This is similar to a frequency histogram but uses a curve rather than bars and accumulates the numbers as we proceed along the x-axis. A variation on the cumulative frequency curve is a dose-response curve used in pharmacology, which you will have encountered.

Question 15

What are the Bubble plots used for?

Answer 15

Bubble plots: This is similar to a scatter plot, but the size of the bubble can represent a third variable. They are good for information visualisation but not always considered scientifically accurate.

Question 16

What are the Stem & leaf plot used for?

Answer 16

Stem & leaf plot: these are similar to a frequency histogram or a dot-plot and display the general distribution of the data. They can be considered as a ‘hybrid’, somewhere between a table and a graph. However, they are only useful for moderately sized data-sets.

Question 17

List 6 types of studies in order of evidence from strongest to weakest

Answer 17

1. Systematic reviews & meta-analyses
2. Randomised control trails
3. Well-designed control trials (non-randomised)
4. Case-control studies
5. Systematic review of descriptive studies
6. Descriptive cross-sectional studies
   7, Case report/series

Question 18

What are levels of evidence?

Answer 18

Evidence is classified according to strength.
- strongest evidence is from analysis of large data sets (e.g. meta-analyses, systematic reviews and randomised controlled trials). Only evidence of this nature can yield strong recommendations.

Non-randomised observational studies such as case-control studies can yield only weak recommendations.

Question 19

What is the risk reduction?

Answer 19

1 - RR

Question 20

What is meant by a 95% confidence intervall?

Answer 20

A 95% confidence interval is a range of values that you can be 95% certain contains the true mean of the population

Question 21

What is relative risk?

Answer 21

The ratio of the probability of an event occurring in the treatment group to the probability of the event occurring in the comparison, placebo group.

RR<1 = lower probability in treatment group e.g. RR of 0.5 indicates risk is halved
RR=1 same probability
RR>1 higher probability in placebo group

Question 22

Define Primary Outcome measure

Answer 22

the outcome that a researcher considers to be the most important among the different outcomes that are to be examined in the study.

Question 23

Define Randomised Controlled Trials

Answer 23

A study in which people are allocated at random (by chance alone) to receive one of several clinical interventions. One of these interventions is the standard of comparison or control. The control may be a standard practice, a placebo (“sugar pill”), or no intervention at all.

Question 24

Define Systematic Reviews

Answer 24

A systematic review summarises the results of available carefully designed healthcare studies (controlled trials) and provides a high level of evidence on the effectiveness of healthcare interventions.

Question 25

Define Meta-analyses

Answer 25

A quantitative, formal, epidemiological study design used to systematically assess the results of previous research to derive conclusions about that body of research.

Question 26

Define Case control studies

Answer 26

A study that:

• compares patients who have a disease or outcome of interest (cases) with patients who do not have the disease or outcome (controls),
• and looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group
• to determine the relationship between the risk factor and the disease.

Case control studies are observational because no intervention is attempted and no attempt is made to alter the course of the disease.

Question 27

Define Relative risk

Answer 27

The ratio of the probability of an event occurring (i.e. skeletal fracture) in the treatment group to the probability of the event occurring in the comparison, placebo group.

Question 28

Define Odds ratio

Answer 28

A measure of association between an exposure and an outcome or the odds of an outcome in the treatment group divided by odds of an outcome in the control group.

If the outcome is negative, an effective treatment will have an odds ratio <1;

If the outcome is positive, an effective treatment will have an odds ratio >1.

Question 29

What does it mean when X^2 is 0?

Answer 29

The observed and expected frequencies are the same

Question 30

The higher the X^2 value…

Answer 30

the bigger the difference between the observed and expected frequencies.