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% Chapter 0 - Proposal
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% Section 1 - Motivation, problem statement and thesis objectives
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\section{Bachelor Thesis Proposal - Philip Gaber}
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{\huge Impact of adjusted, per key, actuation force on efficiency and satisfaction while using mechanical keyboards}
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\subsection{Motivation}
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In recent years, computers are used to some extend in almost every industry in
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Europe \cite{eurostat_ent_w_comp} and China \cite{iresearch_ent_w_comp}. This
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leads to the conclusion, that also other countries must have a high usage of
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computers in corporations. Furthermore, according to a statistic published by
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\citeauthor{itu_hh_w_comp} in 2019, nearly half of the worldwide households have
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access to at least one computer \cite{itu_hh_w_comp}. One of the most used
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devices for data input while operating a computer is the keyboard
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\parencite[22]{handbook_chi}. Therefore, people who use a computer, either at
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home or to fulfill certain tasks at work, are also likely to use a keyboard. An
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important part of a keyboard is the keyswitch also called keyboard key or
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key. Those keyswitches use, depending on the manufacturer or keyboard type,
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different mechanisms to actuate a keypress. More commonly used mechanism to date
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are scissor switches, mostly used in laptop keyboards, dome/membrane switches,
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often used in low- to mid-priced keyboards, and mechanical switches which are
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the main switch type for high-priced and gaming keyboards
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\cite{ergopedia_keyswitch}. Depending on the mechanism and type of key used, it
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is possible that different force has to be applied to the key to activate
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it. Normally, the force required to activate a key is identical for each key
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across the keyboard. However, previous research has shown, that there is a
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disparity in force generated by different fingers
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\cite{bretz_finger_force}. This raises the question, why there are no keyboards
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for personal or work related use cases with adjusted actuation forces per finger
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or even customizable keyboards, where an individual can select the actuation
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force for each keyswitch individually.
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\subsection{Proposed Objective, Research Question and Hypothesis}
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% This thesis is intended to provide an overview of already conducted research in
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% the domain of keyboards, especially in connection with actuation force and the
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% impact of different keyswitches on keyboard users.
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% Because there is no previous research in the particular field of per finger/key
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% actuation force for (mechanical) keyboards and the impact of such customization
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% on efficiency and comfort, this thesis is also intended to research if this is a
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% viable option in comparison to the classic keyboard with uniform actuation
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% force. Therefore the author proposes to answer the question:
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This thesis is intended to research if a keyboard with zones of keys, which have
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adjusted actuation force depending on the assigned finger for that zone and the
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position on the keyboard, is a viable option compared to the standard keyboard
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with uniform actuation force across all keyswitches.
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\begin{tabular}{p{0.3cm} p{0.5cm} p{13cm} p{0.5cm}}
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& \textbf{\large RQ} & {\Large Does an adjusted actuation force per key have a positive impact on efficiency and overall satisfaction while using a mechanical keyboard?} & \\
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\end{tabular}
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\vspace{1em}
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% TODO: Dissatisfied statt comfort da hohe error rate und dadurch frustriert
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% TODO: Bei hypothesen noch error rate bei geschwindigkeit mit einbeziehen
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% ASK: Doch noch comfort mit einbeziehen?
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\begin{longtable}{p{0.3cm} p{0.5cm} p{13cm} p{0.5cm}}
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& \textbf{H1} & Lower key actuation force improves typing speed over higher key actuation force (efficiency - speed). & \\
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& & & \\
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& \textbf{H2} & Higher key actuation force decreases typing errors compared to lower key actuation force (efficiency - error rate). & \\
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& & & \\
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& \textbf{H3} & Keys with lower actuation force are perceived as more satisfactory to write with than keys with higher actuation force. & \\
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& & & \\
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& \textbf{H4} & Users perform better and feel more satisfied while using Keyboards with adjusted key actuation force than without the adjustment. & \\
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\end{longtable}
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\section{Proposed Method}
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\subsection{Subjects}
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It is planned to recruit 20 participants in total. Main target group to recruit
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participants for the research study from are personal contacts and fellow
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students. Participants are required to type with more than just one finger per
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hand. Thus, touch typing is not a mandatory but helpful skill to
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participate. The age distribution for the subjects is estimated to be between 18
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and 56 years. The average typing speed should be known prior to the main
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experiment. Therefore, a typing speed test should be performed on the subject's
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own keyboard in beginning of the experiment. This typing test has to be
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performed within the standardized test environment consisting of an adjustable
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chair, desk, monitor and the typing test software used within the main
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experiment. Also, all subjects have to give their written consent to
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participate in the study.
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\subsection{Study design}
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Participants must complete several typing tests using four different keyboards.
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The experiment should consist of a experimental group and a control group. The
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control group will perform all typing tests with the same keyboard. The text
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used for the typing test should be easily understandable. Therefore, the text
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has to be evaluated with the help of a \gls{FRE} \cite{flesch_fre}
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adjusted for German language \cite{immel_fre}.
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\begin{equation}\label{fre_german}
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FRE_{deutsch} = 180 - \underbrace{ASL}_{\mathclap{\text{Average Sentence Length}}} - (58,5 * \overbrace{ASW}^{\mathclap{\text{Average Syllables per Word}}})
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\end{equation}
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The adjusted formula (\ref{fre_german}) to estimate the understandability of the
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texts used in this experiment usually yields a number in the range of
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\([0;100]\) called the \gls{FRE}. Higher \gls{FRE}s refer to better
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understandability and thus the texts used in this experiment all have to fulfill
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the requirement of a \gls{FRE} \(> 70\), which represents a fairly easy text
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\cite{immel_fre} and \cite{flesch_fre}.
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One typing test will consist of several smaller, randomly chosen, texts
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snippets. The length of the snippets has to be between 100 and 400 characters
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and a snippet has to meet the \gls{FRE} requirement. The snippets are generated by
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volunteers via the web interface of the platform used in this experiment which
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can be seen in appendix \ref{app:gott}.
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% ASK: Should there be a control group at all, if so should they use their own keyboard or always the same random keyboard while they think they are testing different keyswitches?
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After each typing test, the participant has to fill out an adjusted CEN ISO/TS
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9241-411:2014 keyboard comfort questionnaire \cite{iso9241-411}. One additional
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question was added to this questionnaire: ``How satisfied have you been with
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this keyboard?'' The answer for this question can be selected with the help of a
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\gls{VAS} ranging from 0 to 100 \cite{lewis_vas}.
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\textbf{Planned experiment procedure: (Total time requirement: 120 min)}
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\begin{enumerate}
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\item Pre-Test questionnaire to gather demographic and other relevant
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information e.g., touch typist, average \gls{KB} usage per day, predominantly
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used keyboard type, previous medical conditions affecting the result of the
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study e.g., \gls{RSI}, \gls{CTS}, etc. The full questionnaire can be observed
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in the appendix \ref{app:gott}. (5 min)
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\item Adjustment of the test environment (Chair height, monitor height, etc.) (2 min)
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\item Prepare subject for \gls{EMG} measurements: Electrodes are placed on the
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\gls{FDS}/\gls{FDP} and \gls{ED} of both forearms. The main function of the
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\gls{FDS} and \gls{FDP} is the flexion of the medial four digits, while the
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\gls{ED} mainly extends the medial four digits. Therefore, these muscles are
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primarily involved in the finger movements required for typing on a keyboard
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\cite{netter_anatomy}. (8 min)
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\item Familiarization with the typing test and keyboard model used in the experiment. All participants use the same keyboard with 50g actuation force for this step. (5 min)
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\item Initial typing test with own keyboard. (5 min) \\
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Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
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Pause with light stretching exercises. (3 min)
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% SUBTOTAL: 30 min
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\item \textbf{Main Test (H1-H4):} In this part the subject has to
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take two, 5 minute, typing tests per keyboard, with a total of 4
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keyboards (\gls{KB} A, \gls{KB} B, \gls{KB} C, \gls{KB} D). After each
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typing test, the subject has to fill out the post typing test keyboard
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comfort questionnaire. Keyboards A, B and C are equipped with one set of
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keyswitches and therefore each of the keyboards provides one of the
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following, uniform, actuation forces across all keyswitches: 35 \gls{g},
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50 \gls{g} or 80 \gls{g}. These specific values are the results of a
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self conducted comparison between the product lines of most major
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keyswitch manufacturers. The results shown in appendix
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\ref{app:keyswitch} yield, that the lowest broadly available force for
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keyswitches is 35 \gls{g}, the highest broadly available force is 80
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\gls{g}, and the most common offered force is 50 \gls{g}. Keyboard D is
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equipped with different zones of keyswitches that use appropriate
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actuation forces according to finger strength differences and key
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position. The keyboards used in this experiment are visually identical,
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ISO/IEC 9995-1 conform \cite{iso9995-1} and provide a \gls{QWERTZ}
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layout to resemble the subjects day-to-day layout and keyboard format as
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close as possible. All keyboards are equipped with linear mechanical
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keyswitches from one manufacturer to minimize differences in haptic and
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sound while typing. To mitigate order effects, the order of the
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keyboards is counterbalanced with the help of the latin square method
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and the text snippets for the individual tests are randomized
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\cite{statist_counterbalancing}. \textbf{(total: 80 min)}
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\begin{enumerate}
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\item \textbf{\gls{KB} A, Part 1:} Typing test. (5min) \\
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Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
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Pause with light stretching exercises. (3 min)
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\item \textbf{\gls{KB} A, Part 2:} Typing test. (5min) \\
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Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
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Pause with light stretching exercises. (3 min)
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\item \textbf{\gls{KB} C, Part 1:} Typing test. (5min) \\
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Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
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Pause with light stretching exercises. (3 min)
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\item \textbf{\gls{KB} C, Part 2:} Typing test. (5min) \\
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Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
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Pause with light stretching exercises. (3 min)
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\item \textbf{\gls{KB} B, Part 1:} Typing test. (5min) \\
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Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
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Pause with light stretching exercises. (3 min)
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\item \textbf{\gls{KB} B, Part 2:} Typing test. (5min) \\
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Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
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Pause with light stretching exercises. (3 min)
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\item \textbf{\gls{KB} D, Part 1:} Typing test. (5min) \\
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Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
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Pause with light stretching exercises. (3 min)
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\item \textbf{\gls{KB} D, Part 2:} Typing test. (5min) \\
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Adjusted follow-up ISO keyboard comfort questionnaire. (2 min) \\
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Pause with light stretching exercises. (3 min)
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\end{enumerate}
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\item Post-Test semi-structured interview: The participant has to draw three
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different UX curves \cite{kujala_ux_curve} to evaluate how fatigue,
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performance and overall usability of the individual keyboards were perceived
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during the experiment. While drawing the UX curve, participants should
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describe their thought process. To reduce errors in the later evaluation of
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the UX curves, the entire interview is recorded. (10 min)
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\end{enumerate}
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The \gls{EMG} data for all muscles is captured using the Flexvolt Chrome app and Flexvolt 8-Channel
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biosensor device in combination with TIGA-MED ECD-Electrodes. The captured data is then processed and
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plotted using Python. Hardware and plots can be observed in Figure \ref{fig:emg_setup}.
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\begin{figure}[h]
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\centering
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\includegraphics[width=1.0\textwidth]{images/emg_setup.jpg}
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\caption{Flexvolt 8-Channel Biosensor and example plots of \gls{EMG} data}
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\label{fig:emg_setup}
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\end{figure}
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This test scenario is inspired by the tests conducted in \cite{kim_typingforces}.
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