Instruction 15-6
Four Surgical Procedures Currently Are Used to Install

question 2

True/False

Instruction 15-6
Four surgical procedures currently are used to install pacemakers. If the patient does not need to return for follow-up surgery, the operation is called a 'clear' operation. A heart centre wants to compare the proportion of clear operations for the four procedures, and collects the following numbers of patients from their own records:
| Procedure |
$$\begin{array} { | l | c | c | c | c | c | } \hline & \text { A } & \text { B } & \text { C } & \text { D } & \text { Total } \\\hline \text { Clear } & 27 & 41 & 21 & 7 & 96 \\\hline \text { Return } & 11 & 15 & 9 & 11 & 46 \\\hline \text { Total } & 38 & 56 & 30 & 18 & 142 \\\hline\end{array}$$ They will use this information to test for a difference among the proportion of clear operations using a chi-square test with a 0.05 level of significance.
-Referring to Instruction 15-6,there is sufficient evidence to conclude that the proportions between procedure B and procedure D are different at a 0.05 level of significance.

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Definitions:

Weber Fraction

A measure in psychophysics that quantifies the perception of change in a given stimulus relative to its intensity.

Visual Discriminations

The ability to perceive and differentiate visual stimuli and fine details among similar objects or forms.

Auditory Discriminations

The ability to notice, compare, and distinguish between different sounds, integral to language development and communication.

Absolute Threshold

The minimum intensity of a stimulus that one can perceive, below which it is not detected at all.