Science achievement: primary schooling

Why This Is Important

Science is a major influence on many aspects of children's daily lives at play, at school and at home. Science education involves developing skills and knowledge to investigate the living, physical, material, and technological components of the environment and to make sense of them in logical and creative ways.

This indicator draws on the Trends in International Mathematics and Science Study (TIMSS) assessments that included questions on the classification of living things, human health, uses of water, rusting, common energy sources, light, the weather, and changes in the environment.

Indicator

The Item Response Theory (IRT) scaling approach and plausible values methodology is used in PISA. This involved estimating the parameters for each item and examining the background characteristics of the students. From this, estimates of proficiency for each student and IRT scales for reporting student achievement were generated; in aggregate and for each major content domain. Finally, the resulting values were placed on a reporting scale with a mean of 500 and standard deviation of 100.

The IRT analysis provided a common scale on which the performances of students within and across countries may be compared.

Each student has 5 estimates of ability called plausible value (PV1-PV5). The plausible values represent a set of random values for each student selected at random from an estimated ability distribution of students with similar item response patterns and backgrounds. They are intended to provide good estimates of parameters of student populations, for example, country mean scores, rather than estimates of individual student proficiency.

For any group of Year 5 students, for example, the New Zealand Population, Māori, or Girls, the numerator and denominator are defined as follows:

Numerator: (Data source: IEA: Trends in International Mathematics and Science Study (TIMSS))
Sum of the mean science scores for each plausible value for that group.

The mean for each plausible value is defined as:
Numerator: Weighted sum of scores for that group.
Denominator: Sum of the weights for that group (equivalent to the estimated number of students in that group).

Denominator: (Data source: IEA: Trends in International Mathematics and Science Study (TIMSS))
5 (number of plausible values).

Interpretation Issues

Mean TIMSS scores for the New Zealand population and sub-populations are based on scores generated using Item Response Theory. These scores are reported on an international scale with an international standard deviation of 100 so that approximately two-thirds of all students internationally have a score between 400 and 600.

Data for the small proportion of students assessed in Māori in 2002 (~2%) are excluded from trend comparisons over time for New Zealand, to ensure comparability with data reported for 1994, 1998 and 2006. For comparisons with other participating countries in 2002, however, students assessed in Māori are included.

Prioritisation of ethnicity is when people are allocated to one of the ethnicities they have recorded they affiliate with.  This usually occurs when data are collected manually and/or aggregate data returns are collected centrally. This allocation is performed using a predetermined order of ethnic groups. For this indicator ethnicity is prioritised in the order of Māori, Pasifika, Asian, other groups except European/Pākehā, and European/Pākehā. 

For this indicator European/Pākehā refers to people who affiliate as New Zealand European, Other European or European (not further defined).  For example, this includes and is not limited to people who consider themselves as Australian (excluding Australian Aborigines), British and Irish, American, Spanish, and Ukrainian.