Understand Random Sampling - 7th Grade Math

A part of the population that is actually surveyed or measured. It's a subset used to make inferences about the whole.

A sample that reflects the important characteristics of the population. It accurately mirrors the population's key features.

A sample that systematically overrepresents or underrepresents a group. It doesn't accurately reflect population proportions.

Selecting a sample so each member of the population has an equal chance. Every member gets the same probability of selection.

Random sampling. Equal selection chances prevent systematic bias.

Voluntary response sampling. Respondents self-select by choosing to participate.

Convenience sampling. Selects based on easy access, not randomness.

The $50$ surveyed students. The sample is the subset actually measured.

All students at the school. The population is who the survey aims to understand.

The sample must be representative of the population. Only representative samples support valid inferences.

A conclusion about a population based on sample data. It extends sample findings to the larger population.

A sample made of people who choose to respond. Self-selection often creates bias toward strong opinions.

Choosing individuals who are easiest to reach. It prioritizes accessibility over representativeness.

A) survey at a pep rally. Pep rally attendees overrepresent school spirit fans.

A) random sample. Random selection minimizes bias for valid inferences.

B) $30$ chosen by lottery. Lottery gives each student equal selection chance.

Representative. Random selection tends to mirror population traits.

Not valid for the whole population. Biased samples lead to unreliable generalizations.

The population of all students (not just the $100$ sampled).

Using sample data to draw a conclusion about the population.

Survey every $10$th student on a roster.

Online poll link.

All $600$ students at the school.

The $30$ surveyed students.