javelin

Biomechanics of the javelin throw

Biomechanics of the javelin throw: A study to identify the key determinant of a successful

javelin throw for two different skill levels, with the view to improve performance

Abstract

Two right handed female javelin throwers of two different skill levels (novice and elite) were

filmed using 2D analysis completing 6 throws each with a 600g javelin, in order to investig-

ate the key parameter of the technique. Multiple regression was used to analyse the three key

parameters chosen for the study; linear velocity of javelin at release, angle of the right elbow

during the final steps of the withdrawal stage, and the angle of the javelin at release, all in re-

lation to the distance thrown. The data collected, and as hypothesised, revealed that the velo-

city at release showed the greatest variance in the distance thrown for both the novice and

elite with variance levels of 95.5% and 77.9% and respectively. The release angle however

showed no significant variance in the distance for either participant, and the elbow angle was

shown to have a significant positive correlation with the distance for the elite (r=.780) but al-

most no correlation for the novice (r=-.087).

Introduction

Past research on the biomechanics of the javelin throw has indicated that it is a highly com-

plex movement (Atwater, 1979). Many previous studies (e.g. Bartlett & Best, 1988; Ikegami,

1981; Mero, 1994; Navarro, 1994) have tended to analyse a large number of different throw

variables, fewer studies have focused on just a few variables and analysed them in depth.

This study therefore aimed to explore some of the key components during the javelin throw

for two different skill leveled performers. This limited but accurate data will benefit a novice

1


much more than a mass of optimization data on technique that a less competent performer

would not be able to process all at once.

In the throwing of the javelin, as in most other throwing events, the distance thrown depends

largely on the state (for instance the velocity, angle of release and position) of the equipment

at the point of release (Hubbard & Alaways, 1989). When each component of the throwing

skill acts together in a smooth and successful manner, the result can be awe inspiring. The Hi-

erarchical diagram (Figure 1) shows the main factors that contribute towards the overall dis-

tance thrown. This diagram will help to explain the most important parameters.

The hierarchical diagram shows that the angle of the javelin at release and the speed of re-

lease are two key parameters in the determination of the total distance thrown. A number of

studies have analysed the key factor of air resistance (Hatton & Parkes, 2005) and other com-

plex issues of aerodynamics during the flight of the javelin. However, as Hubbard and Rust

(1984) argue, the javelin’s flight path cannot be altered once the javelin is released, therefore

this study focuses on factors that can be adjusted through training.

2

Distance

Distance after releaseDistance prior to release

Position

Height of release

Speed of releaseAngle of release

Air resistance

Forces exerted Distance

Figure 1: Hierarchical diagram for the javelin throw (Hay, 1993)


Hubbard and Alaways (1989) provide a valuable critique of selected experimental javelin lit-

erature focusing on a range of variables and methodological issues. A number of studies

highlight that the velocity of the javelin at release is the most important variable in predicting

distance, such as Komi & Mero’s (1985) significance value of p<0.01. Bartlett et al. (1996)

backed up this statement with a value of p<0.0001 deeming the relationship highly signifi-

cant. More recently Campos et al. (2004) found a correlation index between distance and re-

lease velocity that was high (r: .714) but not statistically significant (p: .072). Dearmond et al.

(1989) found that the distance of the throw is determined by other important predictors such

as height and angle of release point in addition to the velocity of the javelin at release.

Bartlett et al.‘s 1996 study acknowledged that the angle of the elbow during the final steps of

the withdrawal phase are close behind the velocity in terms of the importance of influencing

the throw.

It is clear from past research that the velocity of the javelin at release as well as the angle of

release are important parameters in the technique of the javelin throw. Another variable

deemed of high significance by Bartlett et al. (1996) was that of the angle of the elbow during

the final steps of the withdrawal phase. This final variable can be understood in more depth

through looking at the kinematic chain (Figure 2).

3


The act of the

kinematic

chain on the resultant velocity of the javelin at release is especially important, and if the

thrower is able to bring all their body movements together effectively they can produce an in-

credible amount of acceleration and momentum from which to propel the javelin up and for-

ward at speeds of up to 31mxs-1 (Miller and Munro, 1983). The kinematic chain plays a vital

role during this explosive skill, and coordination of the body parts work up the body from the

feet at the distal point to proximal at the torso, and then from proximal to distal during the re-

lease of the javelin at the hand. By maintaining an extended elbow for as long as possible the

thrower maximizes the possible acceleration path through which to build up speed during the

explosion of the throw. This is backed up by Bartlett, et al. (1996), who concluded in their

study that significantly longer acceleration paths at the start of the delivery stride and a delay

in elbow flexion until final foot strike were important in generating greater release speeds.

This highlights the significance of the kinematic chain, emphasizing the importance of the or-

der in which the body parts move to produce the most powerful movement.

4

Figure 2: Kinematic chain of the javelin throw: actual velocity and time may vary between different skill levels


As seen, the results of experimental research leads practitioners to identify important parame-

ters in order to optimize performance. In light of this, this study chose to analyse the variables

considered to be the key factors in influencing the resulting distance of the throw:

- Joint angle of the elbow during the last few steps of the withdrawal phase (Figure 3)

- Linear velocity of javelin just after release (first finite difference outlined in methods)

- Angle of the javelin at release (Figure 4)

5

Figure 3: Figure showing the relative angle of the elbow to be meaured during the last few steps of the withdrawal phase.


Statement of aims and hypothesis

6


The study aims therefore to analyse these three key independent variables, to identify which

is the best predictor of the dependent variable, distance thrown, by two performers of differ-

ent skill levels. It is hoped that comparison of the findings between skilled and non-skilled

performer will make it possible for the non-skilled to focus on the most important component

of the throwing skill, to improve performance, rather than being distracted by information on

a large number of parameters early on in the development of the skill.

It was hypothesised that one of the three key parameters being studied would reveal the high-

est level of variance in distance deeming it the most influential factor.

Methods

Two right handed females of similar age took part in the study. The elite skilled thrower

came 7th in the National School Championships 2005 and was West of England U20 Javelin

7

Figure 4: Figure showing the absolute angle of the javelin in relation to the horizontal line at the level of the hand to be measured during release


Champion, and the ‘novice’ non-skilled thrower had learnt the basic technique at school. Un-

fortunately due to lack of availability of an athletics track, the study took place on grass at a

local sport facility. However as both participants threw the 600g women’s javelin on the

same surface, the results are still reliable i.e. the measurement was consistent throughout the

study. Tight black clothing was worn so that the reflective joint markers (used to reduce the

chance of human error during digitisation) best represented the actual joints on the right side

of the body, and remained in position. The markers were positioned on the wrist, elbow,

shoulder and hip to provide accuracy for the digitisation process. For scaling purposes during

the digitisation process, a meter ruler was placed where the individuals were to throw, and

was filmed on camera for a few seconds, then taken away for the duration of the filming so as

not to cause injury.

2D analysis was chosen over 3D, using one stationary Sony HVR-A1E HDVcam (25Hz) with

a 1/500s shutter speed filming the complete withdrawal phase and release phase of the throw.

Hubbard & Alaways’ (1989) Meta Analysis provides a useful discussion of video data collec-

tion techniques. Most studies in the analysis of the javelin make use of 3D analysis such as

Bartlett et al. (1996) due to the large number of complex variables to be analysed that occur

in more than one plane of the throwing motion. Studies such as Mero et al. (1994) use two

cameras to examine the body segment contributions to the javelin throw in 2D, whereas the

current study only used one camera due to the smaller number of parameters being studied,

which occur predominantly in only the sagittal plane.

The camera was placed 10m to the side of and in line with the release point. The camera cap-

tured the cross over stride, delivery stride and the release plus the few meters of the javelin’s

path following release in order to be able to calculate the velocity. Six filmed throws were

completed for both participants (having individually warmed up before hand), and the de-

8


pendent variable of the distance was measured using a 100m tape measure from the foul line

to the point where the javelin landed.

Each of the throws for both performer were digitised and analysed using Hu-m-an (Human

movement analysis software, HMA Technology Inc, Ontario, Canada). The two independent

variables were measured using Hu-m-an, except for the release angle which used the Dartfish

software. The linear velocity, which is the rate of change of displacement over time (Hay,

1993) was determined by Hu-m-an using the method of first finite differences outlined be-

low:

Vxi = (xi+1 - xi-1) vyi = (yi+1 - yi-1)2( t) 2( t)

Vr = vx2 + vy

2 = tan-1 vy

vx

(Hu-m-an Environment and reference manual, 2005)

The raw data was then analysed using a hierarchical multiple regression (Figure 1, Appendix

A) technique on SPSS, to determine the most common variance of distance i.e. which of the

three independent variables are the best predictors of the dependent variable and which are

not.

Results

Table 1 above presents a summary of the raw data (which is presented in full in Appendix A:

Table 1A) showing the means and standard deviations for the distance thrown and the three

9


release parameters which were chosen to be analysed in this study. There are clear differ-

ences between the two individuals, with the elite throwing 23.33m further on average. Stan-

dard deviations were much lower overall for the elite except for the velocity of the javelin,

however the velocity averaged 8.1mxs-1 lower for the novice. Release angle appears to be the

only fairly similar variable between the two individuals. Graphs 1, 2 and 3 illustrate these dif-

ferences clearly.

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Graph 2: A scatter graph representing the distance versus velocity for both performers with labelled series reflecting the throw number

Velocity (mxs-

1)

36 1

45

2

1

3

24

5

6

Graph 3: A scatter graph representing the distance versus release angle for both performers labelled series reflecting the throw number

52

3 14

6

1

2

3

4

56


Graph 1 shows the elite performer’s elbow angles to have much less variation with evidence

of a high positive correlation, with higher elbow angles throwing a further distance for the

elite individual. Graph 2 reveals a high positive correlation for the velocity versus distance

for both individuals with the higher velocity thrown by the elite reaching much further dis-

tances. Release angle (graph 3) appears less significant in influencing the distance, with both

individuals sharing similar results, but with the elite still throwing much further and with less

variation.

Pearson’s Correlation (Table 2A) for the elite individual from the hierarchical multiple re-

gression analysis, reveals a significant positive correlation between the two variables of the

release velocity and the elbow angle, and the overall distance thrown (r=.883, p<0.01 for re-

lease velocity; r=.780, p=0.05 for elbow angle). The release velocity is highly significant with

a confidence level higher than 99% that the value of r=.883 did not occur by chance. The re-

lease angle however showed a much lower positive correlation (r=.051) and was deemed not

significant. The velocity accounted for 77.9% of the variance in distance (R2 = .779, p<0.5)

while the angle of the elbow and the release angle accounted for only 12.5% of the variance

(R2 = .125, p>0.05) (Table 3A).

For the novice, Pearson’s Correlation (Table 4A) reveals a significant positive correlation be-

tween the release velocity and the overall distance thrown (r=.978, p<0.01). Similar to the

elite, the novice’s release velocity shows a confidence level higher than 99% that the value of

r=.978 did not occur by chance. The release angle however showed a negative high correla-

tion (r=-.466) while the elbow angle had hardly any correlation at all (r=-.087), with neither

11


being significant. Velocity accounted for 95.5% of the variance in distance (R2 = .956,

p<0.01) while the angle of the elbow and the release angle accounted for only 3.1% of the

variance (R2 = .031, p>0.05) (Table 5A).

Discussion

It must be explained that the ‘elite’ level javelin thrower was of a high standard, however not

quite at the standard of top elite javelin competitors, therefore some of the results may not

quite agree with past research on elite throwers, however the elite should show closer results

to past literature compared to the novice in this study. The significantly greater distances

achieved by the elite level thrower over those of the club level thrower were predominantly

caused by the significant differences in release speed. This therefore supported the hypothesis

that one of the three key parameters that were studied would reveal the highest level of vari-

ance in the distance, deeming it the most influential factor. The release velocities for the elite

thrower (18.95 ± 1.43mxs-1) appear to be not far off data found in previous studies for highly

trained olympic level javelin participants (21.86 ± 1.09mxs-1, Komi & Mero, 1985; 23 ±

1.9mxs-1, Mero et al., 1994). Similarly, the release velocities for the novice (10.82 ±

0.82mxs-1) agree well with past research (10.2 ± 0.97mxs-1, Bartlett et al., 1996).

It should be pointed out, that even though the primary factor in determining distance in this

study is the velocity, it should not be expected to be the only reason for long throws. Like-

wise, although it is an independent variable in relation to the distance in this study, it could

easily be considered a dependent variable, as it is affected by other parameters of the javelin

technique. For instance, it has been clearly noted by Barlett et al. (1996) that the extension of

the elbow during the final stages of withdrawal contributes to maintaining a longer accelera-

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tion path (the distance over which the javelin can be accelerated), therefore maximizing the

velocity built up during the explosion of the throw. According to Best et al. (1993), shorten-

ing of the acceleration path through flexion of the elbow during the final few steps of the

withdrawal should be delayed until late in the kinematic chain sequence of movements. The

significance of this crucial technique in coaching is illustrated in more detail in the coaching

section in Appendix B.

For the elite thrower the elbow angle was in fact the only other parameter analysed which re-

vealed a significant difference with the distance thrown (p=0.05). With a mean elbow angle

of 158.10 ± 3.72, the elite thrower closely agrees with Steve Backley’s (formal world record

holder for men’s javelin) elbow angle result of 156o reported in the Mero et al. (1994) study.

For the novice however, the elbow angle was deemed not significant, highlighting the

novice’s lack of technique in keeping the elbow extended to increase the throwing velocity,

and therefore the distance stated as being very important by Bartlett et al. (1996). The con-

cept of keeping the elbow extended for as long as possible links back to the importance of the

kinematic chain, which the novice does not utilise correctly in order to get the optimum re-

lease velocity. Best et al. (1993) considered limb movement coordination to be extremely im-

portant in terms of determining the differences in javelin throwing ability between different

skill leveled throwers. This has been supported not only by the differences seen in the current

study, but also by differences reported by Mero et al. (1994).

The release angle, which did not show any significant sign of variance in the distance in the

present study, has been recommended by Terauds (1978) to have an optimal release angle of

somewhere between 20o-35o. This however was before the javelin itself was altered slightly

in 1991 in order to reduce the dangerous distances being thrown by some of the men. As

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quoted out by Whiting et al. (1991), “data describing the approach and release parameters of

the new rules javelin performance are limited”. In Whiting et al. (1991, p.112) as well as Best

& Bartlett (1995) an average of 36o for the release angle was found. However, this angle evi-

dently varies between individuals, as Hubbard and Alaways (1987) reported an average angle

or release of 30.84o and Campos et al. (2004) reported a top Olympic athlete to have an aver-

age angle of 41.7o. The release angle of the elite thrower in the current study averaged

41.33o, while the novice averaged 37.83o, however as neither showed any significant vari-

ance in the distance, these results have little meaning. It may have been possible to make out

an optimum throwing angle for both individuals if there had been a larger sample size from

which to analyse the results. With so few results, determining a pattern from looking at the

graph for release angle versus distance is difficult to spot. Ideally a mesokurtic curve would

be seen on a scatter graph, revealing an optimum angle of release, with a normal distribution.

Another important consideration concerns data collection. This study made use of the 2D

technique of video analysis which is defended by Miller & Munro (1983), as very few vari-

ables being studied and all occurring primarily within one plane, 3D analysis was not thought

to be necessary. With regards to the analysis, calculation of the perspective during digitisa-

tion has to be exactly right in order to get the most accurate results. Parallax error can quite

easily occur if the thrower does not throw in exactly the same place that the 1m ruler was

filmed for each throw. The meter ruler was filmed for several seconds as near as possible to

the anticipated release area. However, ensuring that both athletes threw in exactly the same

spot for each of their throws is difficult, possibly resulting in some parallax error occurring.

The linear velocity for both individuals did not quite fit all past research findings, such as

those of Bartlett et al. (1996) who’s results showed figures of around 27mxs-1 for the elite

group, and 15.3mxs-1 for the novice group. It is quite possible that the athletes in this study

14


were throwing slightly further away from the camera than where the meter ruler was placed,

thereby decreasing the calculated apparent velocity of the javelin during the digitisation

process on Hu-m-an.

One caution to be aware of when using multiple regression is that if n is small (for example

three or four pairs of data), there is a possibility that a spuriously high r value can occur by

chance. This is because no factors other than chance would be acting on the variables to

cause the relationship. The study undertaken had 6 pairs of 3 for both throwers (6 throws

analysing 3 different independent variables). In addition, according to Vincent (2005), a key

assumption of multiple regression is that the ratio of subjects to independent variables should

ideally be no less than 5:1. This study had a ratio of 6:3 (i.e 6 throws and 3 variables). Ideally

a higher ratio of subjects to independent variables would be needed, as a reduced ratio “seri-

ously limits the ability to generalise the equation” (Vincent, 2005, p. 117)

One limitation that should be pointed out was the lack of availability of a proper javelin

throwing track. However although this may have altered the results slightly, both individuals

threw under the same conditions making it a fair experiment.

References

Atwater, A.E. (1979). Biomechanics of overarm throwing movements and of throwinginjuries. In R.S. Hutton & D.I. Miller (Eds.), Exercise and sport sciences reviews, 7, 43-85. New York: Franklin Institute Press

15


Bartlett, R.M., & Best, R.J. (1988). The Biomechanics of javelin throwing: a review. Journal of Sports Sciences, 6, 1-38.

Bartlett, R.M., Müller, E., Lindinger, S., Brunner, F., Morris, C. J. (1996). Three-Dimensional Javelin Release Parameters for Throwers of Different Skills Levels.Journal of Applied Biomechanics, 12, 58-71.

Best, R.J., Bartlett, R.M., & Morriss, C.J. (1993). A three-dimensional analysis of javelinthrowing technique at the 1991 World Student Games. JournalofSportsSciences,11, 315-328.

Best, R.J., Bartlett, R.M., & Sawyer, R.A. (1995). Optimal javelin release. Journal Of Ap-plied Biomechanics, 11, 371-394.

Campos, J., Brizuela, G., & Ramon, V. (2004). Three-dimensional kinematic analysis of elite javelin throwers at the 1999 iaaf world championships in athletics. IAAF/NSA, 2(4), Retrieved from http://www.coachr.org/threedimensional_kinematic_analysis_of_elite_javelin_thrower.htm

Dearmond, R., & Semenick, D. (1989). The Javelin throw: a kinesiological analysis with re-commendations for strength and conditioning programming. NSCA Journal, 11(2).

Hay, J.G. (1993). The biomechanics of sports techniques. Englewood Cliffs, NJ: Prentice Hall.

Hatton, L., & Parkes, B. (2005, November). Javelin throwing - the appliance of science. Re-trieved from http://www.leshatton.org/Documents/AW_JavelinArticle_1105.

Hubbard, M., & Alaways, L. (1989). Rapid and accurate estimation of release conditions in the javelin throw. J. Biomechanics, 22(6), 583-595.

Hubbard, M., & Rust, H.J. (1984). Simulation of javelin flight using experimental aerodynamic data. Journal of Biomechanics, 17, 769-776.

Human Movement Analysis (2005). Hu-m-an Environment and reference manual. Ontario: HMA Technology Inc.

Ikegami, Y., Miura, M., Matsui, H., Hashimoto, I. (1981). Biomechanical Analysis ofthe Javelin Throw. In A. Morecki, K. Fidelus (Eds.), Biomechanics VII-B, 271-276. Baltimore: University Park Press.

Komi, P.V., & Mero, A. (1985). Biomechanical analysis of Olympic javelin throwers.International Journal of Sport Biomechanics, 1, 139- 150

Mero, A., Komi, P.V., Korjus, T., Navarro, E., & Gregor, R.J. (1994). Body segment contributions to javelin throwing during final thrust phases. Journal Of Applied Biomechanics, 10, 166-177.

Miller, D.I., & Munro, C.F. (1983) Javelin position and velocity patterns during final foot plant preceding release. J. Hum. Mvt Stud, 9, l-20.

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http://www.coachr.org/threedimensional_kinematic_analysis_of_elite_javelin_thrower.htm

http://www.coachr.org/threedimensional_kinematic_analysis_of_elite_javelin_thrower.htm

http://www.leshatton.org/Documents/AW_JavelinArticle_1105


Navarro, E., Cabrero, O, & Vizcaino, F. (1998). A Procedure for determining the angular ve-locity of the upper arm about its longitudinal axis relative to the thorax in javelin throwing. Proceedings of the Isbs congress http://www.isbs.org/.

Terauds, J. (1978). Computerized biomechanical analysis of selected javelin throwers at the 1976 Montreal Olympiad. Track and Field Quarterly Review, 1, 29-31.

Vincent, W.J. (2005). Statistics in kinesiology. Leeds: Human Kinetics.

Whiting, W.C., Gregor, R.J., & Halushka, M. (1991). Body segment and release parameter contributions to new-rules javelin throwing. International Journal of Sport Biome-

chanics , 7, 111-124.

Appendix A

Multiple regression

Figure 1 below highlights the equation for multiple regression:

17

http://www.isbs.org/


Y=b1X1+b2X2+b3X3......b7X7+C (Figure 1)

Where Y is the dependent variable, X1 is an independent variable, b1 is the regression coeffi-cient for X1 etc and C is a constant.

18

Table 1A: The raw data collected for both participants (E. stands for Elite and N. stands for Novice)

–E. 1stE. 2ndE. 3rdE. 4thE. 5thE. 6thElbow angle during 156162.2152157.6160.5160.3withdrawal (degrees)± 4.13± 2.40± 4.47± 3.54± 1.80± 3.54Javelin release velocity (m x s-1)18.52117192018Release angle (degrees)404637443645Distance (m)3940.738.540.0541.439.3N. 1stN. 2ndN. 3rdN. 4thN. 5thN. 6thElbow angle during 112.5106.1128.9127.6118.6122.3withdrawal (degrees) ± 2.98± 5.90± 7.41± 5.39± 3.50± 6.45Javelin release velocity (m x s-1)121111.510.51010Release angle (degrees)323842294640Distance (m)20.416.218.716.313.913.5


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Table 3A: Elite thrower

Table 2A highlights a significant positive correlation between the two variables of the release velocity and the elbow angle, and the overall distance thrown (r=.883, p<0.01 for release velocity; r=.780, p=0.05 for elbow angle). The angle of the javelin at release shows a lower positive correlation (r=.051) and was deemed not significant.

Overall distance thrownVelocity of javelin at releaseElbow angle during withdrawalAngle of javelin at releasePearson

Correlation Overall distance thrown Velocity of javelin at release Elbow angle during withdrawal

Angle of javelin at release1.000

.883

.780

.051.883

1.000

.814

.317.780

.814

1.000

.532.051

.317

.532

1.000Sig. (1-tailed) Overall distance thrown

Velocity of javelin at release Elbow angle during withdrawal

Angle of javelin at release.

.010

.034

.462.010

.

.024

.270.034

.024

.

.139.462

.270

.139

.N Overall distance thrown


Angle of javelin at release6

6

6

66

6

6

66

6

6

66

6

6

6

CorrelationsTable 2A: Elite thrower

Table 3A shows the model summary from the heirarchical multiple regression analysis. It shows what the dependent variable was and what the predictors were in each of the two models. Collumn R shows the multiple correlation coefficient between the predictors and the outcome, while R2 is a measure of how much of the variability in the outcome is accounted for by the predictors.

Table 5A: Novice thrower

Table 4A highlights a significant positive correlation between the of the release velocity and the overall distance thrown (r=.978, p<0.01). The release angle shows a negative high correlation (r=-.466) while the elbow angle has hardly any correlation at all (r=-.087), with both being deemed not significant.

Overall distance thrownVelocity of javelin at releaseElbow angle during withdrawalAngle of javelin at releasePearson

Correlation Overall distance thrown Velocity of javelin at release Elbow angle during withdrawal

Angle of javelin at release1.000

.978

-.097

-.466.978

1.000

-.233

-.374-.087

-.233

1.000

.018-.466

-.374

.018

1.000Sig. (1-tailed) Overall distance thrown


Angle of javelin at release.

.000

.435

.176.000

.

.328

.233.435

.328

.

.487.176

.233

.487

.N Overall distance thrown


Angle of javelin at release6

6

6

66

6

6

66

6

6

66

6

6

6

CorrelationsTable 4A: Novice thrower

Table 5A shows the model summary from the heirarchical multiple regression analysis. It shows what the dependent variable was and what the predictors were in each of the two models. Collumn R shows the multiple correlation coefficient between the predictors and the outcome, while R2 is a measure of how much of the variability in the outcome is accounted for by the predictors.