STP Data Analysis 3

Question 1

A researcher finds a p-value of 0.03. This means:

Accepted Answer

There is a 3% probability of obtaining these results if the null hypothesis is true

Answer

A p-value represents the probability of obtaining the observed results (or more extreme) assuming the null hypothesis is true.

Question 2

Which type of error occurs when a true null hypothesis is incorrectly rejected?

Accepted Answer

Type I error

Answer

A Type I error (false positive) occurs when the null hypothesis is rejected despite being true, with probability equal to alpha.

Question 3

In receiver operating characteristic (ROC) analysis, an AUC of 0.5 indicates:

Accepted Answer

A test no better than random chance

Answer

An AUC of 0.5 corresponds to the diagonal line, meaning the test performs no better than random chance at discrimination.

Question 4

What does a box-and-whisker plot's interquartile range (IQR) represent?

Accepted Answer

The middle 50% of the data

Answer

The IQR spans from the 25th to the 75th percentile, encompassing the middle 50% of observations.

Question 5

When laboratory data shows positive skewness, the appropriate measure of central tendency is:

Accepted Answer

Median

Answer

The median is preferred for skewed data as it is not influenced by extreme values that pull the mean in the direction of the skew.

(STP) Scientist Training Programme Practice Test