ANALISIS KESALAHAN MAHASISWA DALAM MENURUNKAN SIFAT-SIFAT VARIANSI DAN SIMPANGAN BAKU

Variance and standard deviation are the materials in Statistical method course. Variance and
standard deviation become the main focus in this study. The researcher found that there are some
students who still make mistakes in lowering the properties of variance and standard deviation.
This study aims to describe the mistakes made by students in reducing the properties of variance
and standard deviation. This research is a qualitative descriptive research which is conducted at
State University of Malang. The participant of this study is the mathematics student offering A on
period 2015/2016. The validity of data have been checked through triangulation and peer
examinations. The data were obtained by test and interviews. The results of study reported some
conceptual and procedural mistakes made by student and also the factors that cause mistakes. The
conceptual mistakes made by students are misunderstanding the formula and symbols,
misconceptions mean, misunderstanding the nature of addition to sigma notation and also
misunderstanding the power and multiplication distribution. The procedural mistakes made by
students involve the mistake in writing formula and symbols, distributing number and solving
procedure. The factors that cause the mistakes made by students are lack of prior knowledge about
the nature of addition of sigma notation, less carefulness when solving the test and less of memory
about the mathematical concepts that have been learned earlier.
Keywords: Mistake, reducing the properties, variance, standard deviation