4.2 Percentages and odds

In a study of how well emergency dispatchers recognised signs of stroke (Oostema et al. 2018), the data shown below were collected.

Sex of patients	Dispatcher suspected stroke	Dispatcher missed stroke
Male	67	43
Female	97	39

What proportion of patients had their stroke symptoms missed?
Sketch a side-by-side or stacked bar chart to display the data.
Of the male patients, what proportion had their stroke symptoms missed by the dispatcher?

0.391 0.609 0.524 0.333
Of the female patients, what proportion had their stroke symptoms missed by the dispatcher?

0.713 0.476 0.287 0.333
For the male patients, what are the odds that they had their stroke symptoms missed by the dispatcher?

39.1 0.642 0.907 0.50
For the female patients, what are the odds that they had their stroke symptoms missed by the dispatcher?

0.402 2.49 1.10 1.24
What is the difference between the proportions of stroke symptoms being missed by the dispatcher, comparing males to females?

0.391 1.6 0.104 0.287
What is the odds ratio that a patients had their stroke symptoms missed by the dispatcher, comparing males to females?

0.63 0.402 0.50 1.6
Construct a numerical summary table (see Table 4.1).

TABLE 4.1: Summary table: emergency dispatchers and missing stroke symptoms. Enter PROPORTIONS and ODDS to TWO decimal places.
	Proportion	Odds	Sample
	symptoms missed	symptoms missed	size
Males
Females
	Difference:	Odds ratio:

References

Oostema JA, Chassee T, Reeves M. Emergency dispatcher stroke recognition: Associations with downstream care. Prehospital Emergency Care. 2018;22(4):466–71.