title: Incorporating context effects into a choice model

authors: Rooderkerk, Robert P.

subjects: context effects

abstract: The behavioral literature provides ample evidence that consumer preferences are partly driven by the context provided by the set of alternatives. Three important context effects are the compromise, attraction, and similarity effects. Because these context effects affect choices in a systematic and predictable way, it should be possible to incorporate them in a choice model. However, the literature does not offer such a choice model. This study fills this gap by proposing a discrete-choice model that decomposes a product’s utility into a context free partworth utility and a context-dependent component capturing all three context effects. Model estimation results on choice-based conjoint data involving digital cameras provide convincing statistical evidence for context effects. The estimated context effects are consistent with the predictions from the behavioral literature, and accounting for context effects leads to better predictions both in and out of sample. To illustrate the benefit from incorporating context effects in a choice model, the authors discuss how firms could utilize the context sensitivity of consumers to design more profitable product lines.

text: Incorporating context effects into a choice model The behavioral literature provides ample evidence that consumer preferences are partly driven by the context provided by the set of alternatives. Three important context effects are the compromise, attraction, and similarity effects. Because these context effects affect choices in a systematic and predictable way, it should be possible to incorporate them in a choice model. However, the literature does not offer such a choice model. This study fills this gap by proposing a discrete-choice model that decomposes a product’s utility into a context free partworth utility and a context-dependent component capturing all three context effects. Model estimation results on choice-based conjoint data involving digital cameras provide convincing statistical evidence for context effects. The estimated context effects are consistent with the predictions from the behavioral literature, and accounting for context effects leads to better predictions both in and out of sample. To illustrate the benefit from incorporating context effects in a choice model, the authors discuss how firms could utilize the context sensitivity of consumers to design more profitable product lines.

year: 2011

title: The stability reliability, and utilisation of the isometric belt when measuring changes in strength across a professional Rugby Union competition.

authors: Danby, Ryan

abstract: Many athletes target an increase in strength in order to improve sporting performance. Specific to Rugby Union,
an increase in strength has shown to distinguish between levels of competition, and as such, measuring strength
is required for the implementation and monitoring of effective training programs. Traditionally, one-repetition
maximum (1-RM) testing has been implemented as it is a direct measure of dynamic strength that is commonly
incorporated into training programs. However, 1-RM testing is not very practical in-season and research suggests
it is less safe and produces more fatigue than alternate methods of testing. Isometric testing is an alternative to 1-
RM testing that has been shown to be reliable and effective at reducing testing time and reducing fatigue, loading,
and injury risk. Anecdotally, however, isometric testing such as the isometric mid-thigh pull, and isometric back
squat are less feasible in season due to the injuries Rugby Union athletes obtain. An alternative isometric test is
an isometric belt squat which is strictly a lower-body method of evaluating strength; however, to date, the
reliability and effectiveness of the isometric belt squat is unknown.

This thesis is separated into four chapters. Chapter One is a review of literature that highlights the importance of
strength in sport, the changes in strength athletes sustain throughout a season, how reliability can be measured,
the traditional methods of strength testing, isometric testing, and the specific methods of isometric testing
commonly used in Rugby Union. The literature shows the isometric mid-thigh pull, and isometric squat are
reliable methods of measuring strength that have been shown to correlate to 1-RM testing. Previous research
comparing the isometric belt squat to an isometric squat show a reduction in lower-back stress and an increase in
peak vertical force in the isometric belt squat, suggesting it is a potentially safer and more accurate evaluation of
lower-body strength for athletes. However, there is no research into the stability reliability of the isometric belt
squat. Furthermore, the literature has shown that while in competition, an increase in skill training results in a
decrease in resistance training to balance training load while maintaining concurrent training. Therefore,
periodised training programs are required in-season to minimise the negative effects concurrent training has on
the maintenance/development of strength. As concurrent training conflicts with an increase in strength within a
season and the evaluation of the fluctuations of strength levels helps guide training programs, valid and reliable
strength testing is required to inform effective exercise prescription.

Chapter Two investigated the reliability of the isometric belt squat. Both between- and within-session reliability
were measured during a five-week investigation with each athlete completing the isometric belt squat four times.
Intraclass correlation coefficients (ICC), coefficient of variation (CV), typical error (TE), smallest worthwhile
change (SWC), and p-values were calculated to assess the reliability between-sessions, whereas a CV was used
to quantify within-session reliability. The between-session reliability indicated the isometric belt squat was a
reliable measure of strength after each athlete had completed one familiarisation period with a range of measures
deemed reliable between Trials 2 and 4 (TE= 504.56 N, CV = 8.7%, ICC = 0.86, p-value = 0.021, SWC0.5 =
647.39 N). The within-session data was also considered reliable which was conducted after the familiarisation
period (CV = 7.2%). Overall, the between- and within-session data indicated the isometric belt squat test is a
reliable measure once each athlete has completed one familiarisation trial.

Chapter Three investigated the change in strength that occurred in professional Rugby Union athletes across a
competitive season. This study was conducted over a 15-week block (end of preseason to end of competition)
whereby each athlete completed five trials of the isometric belt squat. Effect size (ES), probability statistics, and
a percentage of change in strength were used to highlight the change in strength between the five trials. Overall,
the change in strength from Trial 1 to 5 was ‘trivial’ (+0.44%, ES = 0.04, p value = 0.871). The ‘trivial’ increase
in strength across the season indicates the maintenance of strength from the end of preseason to end of competition
is feasible despite the interference concurrent training imposes.

Overall, as concluded in Chapter Four, the results from the two studies in this thesis show that the isometric belt
squat is a reliable measure of strength both between- and within-sessions once each athlete has completed one
familiarisation period, and that strength can be maintained across a professional rugby union season. The limited
literature surrounding the isometric belt squats reliability when applied to Rugby Union, and the change in strength
across a competitive Rugby Union season is an area that needed to be addressed. This thesis described the literature
surrounding isometric testing, identified the stability reliability of a isometric belt squat, and assessed strength
changes across a season in professional Rugby Union athletes. This information can be used to enhance strength
monitoring in professional team sports such as Rugby Union, Rugby League, Football, and Netball that have
access to force plates or strain gauges.

text: The stability reliability, and utilisation of the isometric belt when measuring changes in strength across a professional Rugby Union competition. Many athletes target an increase in strength in order to improve sporting performance. Specific to Rugby Union,
an increase in strength has shown to distinguish between levels of competition, and as such, measuring strength
is required for the implementation and monitoring of effective training programs. Traditionally, one-repetition
maximum (1-RM) testing has been implemented as it is a direct measure of dynamic strength that is commonly
incorporated into training programs. However, 1-RM testing is not very practical in-season and research suggests
it is less safe and produces more fatigue than alternate methods of testing. Isometric testing is an alternative to 1-
RM testing that has been shown to be reliable and effective at reducing testing time and reducing fatigue, loading,
and injury risk. Anecdotally, however, isometric testing such as the isometric mid-thigh pull, and isometric back
squat are less feasible in season due to the injuries Rugby Union athletes obtain. An alternative isometric test is
an isometric belt squat which is strictly a lower-body method of evaluating strength; however, to date, the
reliability and effectiveness of the isometric belt squat is unknown.

This thesis is separated into four chapters. Chapter One is a review of literature that highlights the importance of
strength in sport, the changes in strength athletes sustain throughout a season, how reliability can be measured,
the traditional methods of strength testing, isometric testing, and the specific methods of isometric testing
commonly used in Rugby Union. The literature shows the isometric mid-thigh pull, and isometric squat are
reliable methods of measuring strength that have been shown to correlate to 1-RM testing. Previous research
comparing the isometric belt squat to an isometric squat show a reduction in lower-back stress and an increase in
peak vertical force in the isometric belt squat, suggesting it is a potentially safer and more accurate evaluation of
lower-body strength for athletes. However, there is no research into the stability reliability of the isometric belt
squat. Furthermore, the literature has shown that while in competition, an increase in skill training results in a
decrease in resistance training to balance training load while maintaining concurrent training. Therefore,
periodised training programs are required in-season to minimise the negative effects concurrent training has on
the maintenance/development of strength. As concurrent training conflicts with an increase in strength within a
season and the evaluation of the fluctuations of strength levels helps guide training programs, valid and reliable
strength testing is required to inform effective exercise prescription.

Chapter Two investigated the reliability of the isometric belt squat. Both between- and within-session reliability
were measured during a five-week investigation with each athlete completing the isometric belt squat four times.
Intraclass correlation coefficients (ICC), coefficient of variation (CV), typical error (TE), smallest worthwhile
change (SWC), and p-values were calculated to assess the reliability between-sessions, whereas a CV was used
to quantify within-session reliability. The between-session reliability indicated the isometric belt squat was a
reliable measure of strength after each athlete had completed one familiarisation period with a range of measures
deemed reliable between Trials 2 and 4 (TE= 504.56 N, CV = 8.7%, ICC = 0.86, p-value = 0.021, SWC0.5 =
647.39 N). The within-session data was also considered reliable which was conducted after the familiarisation
period (CV = 7.2%). Overall, the between- and within-session data indicated the isometric belt squat test is a
reliable measure once each athlete has completed one familiarisation trial.

Chapter Three investigated the change in strength that occurred in professional Rugby Union athletes across a
competitive season. This study was conducted over a 15-week block (end of preseason to end of competition)
whereby each athlete completed five trials of the isometric belt squat. Effect size (ES), probability statistics, and
a percentage of change in strength were used to highlight the change in strength between the five trials. Overall,
the change in strength from Trial 1 to 5 was ‘trivial’ (+0.44%, ES = 0.04, p value = 0.871). The ‘trivial’ increase
in strength across the season indicates the maintenance of strength from the end of preseason to end of competition
is feasible despite the interference concurrent training imposes.

Overall, as concluded in Chapter Four, the results from the two studies in this thesis show that the isometric belt
squat is a reliable measure of strength both between- and within-sessions once each athlete has completed one
familiarisation period, and that strength can be maintained across a professional rugby union season. The limited
literature surrounding the isometric belt squats reliability when applied to Rugby Union, and the change in strength
across a competitive Rugby Union season is an area that needed to be addressed. This thesis described the literature
surrounding isometric testing, identified the stability reliability of a isometric belt squat, and assessed strength
changes across a season in professional Rugby Union athletes. This information can be used to enhance strength
monitoring in professional team sports such as Rugby Union, Rugby League, Football, and Netball that have
access to force plates or strain gauges.

year: 2024-09-02

title: Challenges to legal education: The Waikato Law School experience

authors: Wilson, Margaret

subjects: legal education

abstract: The experiences of the Waikato Law School especially from the viewpoint of challenges to legal education are discussed. The impact of the performance-based model of funding on the delivery of legal education at the Waikato Law School is highlighted.

text: Challenges to legal education: The Waikato Law School experience The experiences of the Waikato Law School especially from the viewpoint of challenges to legal education are discussed. The impact of the performance-based model of funding on the delivery of legal education at the Waikato Law School is highlighted.

year: 2010