| Date | November 2021 | Marks available | 3 | Reference code | 21N.2.SL.tz0.1 |
| Level | Standard Level | Paper | Paper 2 | Time zone | time zone 0 |
| Command term | Comment | Question number | 1 | Adapted from | N/A |
Question
A study investigated the effect of three different sports on force–time variables during a vertical jump performed by elite athletes. The variables measured were time during the eccentric phase (when the quadriceps lengthen to prepare for the jump), total jump time (eccentric and concentric phases), eccentric rate of force development, and jump height.
Table 1: Mean and standard deviation (SD) for the force–time variable data
[Source: Laffaye, G., et al., 2014. Countermovement jump height: gender and sport-specific differences in the force-time
variables. Journal of Strength and Conditioning Research, 28(4), pp. 1096–1105. Source adapted.]
Identify the sport with the greatest mean jump height.
Calculate the difference between mean eccentric rate of force development for baseball and basketball.
Using the data from Table 1, analyse the differences in force–time variables for basketball, football and baseball players.
Identify the sport with the smallest standard deviation for eccentric rate of force development.
Comment on the meaning of the standard deviation with reference to Table 1.
Markscheme
football;
5.41 − 3.37;
= 2.04 < kN s–1 >;
eccentric time:
basketball players have the highest / footballers have the lowest eccentric times;
total jump time:
baseball has the highest jump time / basketball and baseball players have similar jump time/ footballers have the lowest jump time;
eccentric rate of force development:
baseball players have the highest / basketballers have the lowest rate of eccentric force development;
jump height:
baseball players have the lowest height / basketball and baseball players have similar jump heights/ footballers have the highest jump height;
baseball;
the small standard deviation e.g. total jump time for baseball, indicates that the data is clustered around the mean;
a large standard deviation e.g. jump height for football can indicate that there is an issue with reliability;
most of the data has a relatively small standard deviation with the exception of jump height which suggests that there is a little variation in performance;
jump height appears to be the least reliable force–time variable;
the standard deviations for every sport for a particular measure are similar e.g. for eccentric time they range from 5, 7 and 8;
Award [1 max] if there is no reference to data.
Accept answer that refers to relative proportion of the SD to mean.
Note: statistical significance cannot be determined from the data.
Accept in the converse.
Examiners report
The calculations and analysis of the graph was done very well. Overall, candidates had selected the correct data for the calculation, gave extensive analysis of the force–time variables for the full 3 marks and could identify the correct standard deviation.
Most candidates started this answer with the definition which did not gain a mark and then followed up by referring to the data as intended by the question. Candidates struggled to access the full 3 marks for this question.
