Statistically based reports key terms NCEA level 3

Variable

A feature thats able to change

Explainatory variable

The thing that's controlled and changed. It's usually the cause or the explanation of the other variable

Response/outcome Variable

The focus. We measure how much it changes when the explanatory variable changes

Confounding variables

Outside factors that affect the study results and are not controlled

evaluate

This means you find whether surveys are true, fair, unbiased and well-represented, or not

Causal claim

Saying that the explanatory variable directly causes the response variable to change

Sampling

When we take a small group from the population and use it to represent the entire population

Bias

When a sample tends to get a particular kind of answer that is different from the truth, because we picked a bad sample or asked bad questions

Sampling Bias

When a sample over represents or under represents certain groups in the population, so the sample is not representative.

True population value

The real stats of the real population. This is what we want to have a guess at using our samples

Sampling errors

These happen because data is collected from a sample rather than the whole population

Non sampling error

These happen if a sample has bias or doesn't accurately represent the population

Margin of error

A distance from the sample stats that we are pretty 95% sure the population stats falls within

Correlation

When both variables change. As one variable changes, the other one tends to, but this does not mean they make each other change.

Causality

When one variable causes another. As one changes, it makes the other change

Random sampling

When each bit of the population is numbered off and has an equal chance of being selected.

Systematic sampling

When parts of a population are ordered and then every one is picked from a random starting point

stratified sampling

a variation of random sampling; the population is divided into subgroups and weighted based on demographic characteristics of the national population

cluster sampling

When you grab whole groups and use that as your sample

Quota sampling

When the researcher has to have a certain amount of minority groups in their sample so they are not under represented or ignored

self selected sample

Text-votes, phone calls or voluntary surveys