In this graph, what does the green arrow respresent? Choose from the following.
Continuing with the systolic blood pressure example (questions 1-10), use the following diagram to answer the question below.
O The green arrow represents which of the following?
O The mean systolic blood pressure for this sample
O The values within which 68.2% of systolic blood pressures will fall
O The values within which 99% of systolic blood pressures will fall
O The probability of a systolic blood pressure between 83 mm Hg and 138 mm Hg
O The probability of a systolic blood pressure between 83 mm Hg and the mean
O The values for systolic blood pressure of 83 and 138
O The values for systolic blood pressure of 83 and 138
O The values within which 95% of systolic blood pressures will fall
O The probability of a systolic blood pressure between the mean and 138 mm Hg
The correct answer and explanation is:
The correct answer is:
“The values within which 95% of systolic blood pressures will fall.”
Explanation:
The diagram you provided is a normal distribution curve, which is commonly used to represent the distribution of systolic blood pressure in a population. In statistics, the normal distribution (also known as the bell curve) helps determine the probability of a variable falling within a specific range.
In this case, the green arrow is likely pointing to the range that contains 95% of the data. This range is determined by the empirical rule, which states that:
- 68.2% of values fall within one standard deviation (±1σ) from the mean.
- 95% of values fall within two standard deviations (±2σ) from the mean.
- 99.7% of values fall within three standard deviations (±3σ) from the mean.
Since the question asks about the green arrow and the given options include a reference to 95%, this means that the arrow is likely indicating the interval that covers two standard deviations from the mean, or approximately 95% of the distribution.
This means that if we were to randomly select a systolic blood pressure measurement from this sample, there is a 95% probability that it will fall within this range. The two values (83 mm Hg and 138 mm Hg) likely represent the lower and upper bounds of this confidence interval.
Understanding this concept is crucial in medical studies, as it allows researchers to determine the expected range of systolic blood pressures in a population and identify outliers that may indicate health risks such as hypertension or hypotension.