Health professionals warn that transmission of infectious...

Health professionals warn that transmission of infectious diseases may occur during the traditional handshake greeting. Two alternative methods of greeting (popularized in sports) are the "high five" and the "fist bump." Researchers compared the hygiene of these alternative greetings in a designed study and reported the results in the $A$ merican Journal of Infection Control (Aug. 2014). A sterile-gloved hand was dipped into a culture of bacteria, then made contact for three seconds with another sterile-gloved hand via either a handshake, high five, or fist bump. The researchers then counted the number of bacteria present on the second, recipient, gloved hand. This experiment was replicated five times for each contact method. Simulated data (recorded as a percentage relative to the mean of the handshake), based on information provided by the journal article, are provided in the table. $$ \begin{array}{lrrrrr} \hline \text { Handshake: } & 131 & 74 & 129 & 96 & 92 \\ \text { High five: } & 44 & 70 & 69 & 43 & 53 \\ \text { Fist bump: } & 15 & 14 & 21 & 29 & 21 \\ \hline \end{array} $$ a. The researchers reported that "[more] bacteria were transferred during a handshake compared with a high five." Use a $95 \%$ confidence interval to support this statement statistically. b. The researchers also reported that "the fist bump ... gave [a lower] transmission of bacteria" than the high five. Use a $95 \%$ confidence interval to support this statement statistically. c. Based on the results, parts a and $\mathbf{b}$, which greeting method would you recommend as having the most hygiene?

Health professionals warn that transmission of infectious diseases may occur during the traditional handshake greeting. Two alternative methods of greeting (popularized in sports) are the "high five" and the "fist bump." Researchers compared the hygiene of these alternative greetings in a designed study and reported the results in the $A$ merican Journal of Infection Control (Aug. 2014). A sterile-gloved hand was dipped into a culture of bacteria, then made contact for three seconds with another sterile-gloved hand via either a handshake, high five, or fist bump. The researchers then counted the number of bacteria present on the second, recipient, gloved hand. This experiment was replicated five times for each contact method. Simulated data (recorded as a percentage relative to the mean of the handshake), based on information provided by the journal article, are provided in the table.
$$
\begin{array}{lrrrrr}
\hline \text { Handshake: } & 131 & 74 & 129 & 96 & 92 \\
\text { High five: } & 44 & 70 & 69 & 43 & 53 \\
\text { Fist bump: } & 15 & 14 & 21 & 29 & 21 \\
\hline
\end{array}
$$
a. The researchers reported that "[more] bacteria were transferred during a handshake compared with a high five." Use a $95 \%$ confidence interval to support this statement statistically.
b. The researchers also reported that "the fist bump ... gave [a lower] transmission of bacteria" than the high five. Use a $95 \%$ confidence interval to support this statement statistically.
c. Based on the results, parts a and $\mathbf{b}$, which greeting method would you recommend as having the most hygiene?

Key Concepts

Statistical Significance

Statistical significance refers to the likelihood that an observed difference or relationship in the data is not due to random chance. By using techniques such as confidence intervals or p-values, researchers can infer whether the differences observed between groups are meaningful. If a confidence interval for the difference between two means does not contain zero, this suggests that the difference is statistically significant.

Confidence Interval

A confidence interval is a range of values, derived from sample data, that is likely to contain the true population parameter with a specified level of confidence (in this case, 95%). It provides a measure of precision around an estimate and is used to assess the reliability of a statistical estimate, allowing one to determine if differences between groups are likely to be real rather than due to random variability.

Experimental Design

Experimental design involves planning the procedure of an experiment to ensure valid and unbiased results. This includes factors such as controlling conditions, replication of experiments, random assignment of treatments, and blinding where possible. Good experimental design minimizes the influence of confounding factors and allows for more accurate interpretation of cause-and-effect relationships.

Comparison of Group Means

Comparison of group means is a common statistical technique used to evaluate whether there are significant differences between the average values of different groups. This concept is crucial when testing hypotheses about differences in performance, behavior, or other outcomes between groups under different conditions, and it often involves the use of confidence intervals or hypothesis tests to determine the statistical significance of the observed differences.

Transcript

00:01 Here's a solution for problem number 924.

00:03 So we're looking at hygiene of handshakes, high fives, and fist bumps.

00:08 And we're given some data, and i actually put in the data already.

00:11 So if you go to stat and then edit, here is the number of bacteria for a handshake.

00:18 And then l2 is for a high five, and then l3 is a fist bump.

00:22 So researchers reported that as part a that more bacteria were transferred during a handshake compared with a high five.

00:28 So we need to compare l1 with l2.

00:31 And we're going to use a 95 % confidence interval to support that statement statistically.

00:35 So if we go to stat and then tests, and we're going to go down to two sample t intervals since this is a small sample size.

00:42 And we want to be 95 % confident here, so 0 .95.

00:46 And we're using l1 and l2 since that's the handshake versus the high five.

00:51 And whenever we calculate, we get 19 .669 to 77 .531.

00:59 Let's write those down.

01:00 So we have 19 .665 to or 669, 77 .531.

01:18 Okay, so that means that we can be 95 % confident that the difference between the handshake minus the high five is between 77 .531 and 19 .669 bacteria.

01:34 So since zero is not contained in that interval, then we can be 95 % confident that there is a difference...

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