Page 190 - Math Course 3 (Book 2)

Understanding Proportions and Ratios
Mo. 12

Lesson 3 systematic random sample

a sample in which the items or people are selected
according to a specific time or item interval.

KEY CONCEPTS: One of every 5 students to enter the school
gate is selected.
1. Identify various sampling techniques.
2. Determine the validity of a sample and Every 5 minutes, one student is selected
predict the actions of a larger group. from those entering the gate.

simple random sample
MO. 12 - L3a
a sample where each item or person in a
Introduction to Sampling and population is as likely to be chosen as any other.
Prediction Thirty students are randomly selected by a
computer based on Student ID number.

Vocabulary A-Z stratified random sample

Let us learn some vocabulary a sample in which the population is divided into
similar, non-overlapping groups.

A simple random sample is then selected from
each group.

Students are divided into groups based on
the month of their birthday. Five students
are selected from each of the 12 months.

sample biased sample
In a survey of a larger group, a randomly selected A sample that is not representative of the
smaller group within the original group is a called population is called biased sample.
sample.
Only students who scored between who
Smaller group inside the magnifying glass is the scored between 60% – 70% on the final
sample. exam are selected.

population
The larger group from which the sample is taken is convenience sample
called the population. a sample which includes members of the
population that are easily accessed.
All the people in the group to select from are the
population. Only students who live within 1 kilometer of
the school are selected.
unbiased sample
is a sample that is:
• representative of the larger population voluntary response sample
• selected at random or without preference, and a sample which involves only those who want to
• large enough to provide accurate data. participate in the sampling.

75% of all the student at the school from
all the grade levels are selected randomly Only students whose volunteer are selected.
using a computer.

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