math statistics YR8

What is a Mean?

Average

What is a Median?

middle score in an ordered numerical data set

What is a Mode?

most frequently occurring score

What is a Range?

the difference between the highest and lowest score

What is the best data measurement for a data that doesn't have any extreme values or outliers?

Mean

What is the best data measurement for a data that has extreme values or outliers?

Median

WHat is the best data measurement for a data that has repeated numbers?

Mode

How do you find the Total Sum of All Scores from a bar chart?

Multiply each Score by its Frequency, then add them all together.

how do you find the total number of scores to divide it with the total sum of all scores?

Add all the frequencies (bar heights)

What is a normal distribution?

normal distribution is like a bell shaped curve where the mean, mode, and median has equal or similar values

What is a uniform distribution?

A distribution where all values have the same frequency.

What is a positive skew?

A type of distribution in which the right side is stretched out.

What is a negative skew?

A type of distribution in which the left side is stretched out.

What changes about the Range when you remove the outlier?

The Range will always decrease

What changes about the Median when you remove the outlier?

The Median might increase or decrease

What changes about the Mean when you remove the outlier

The Mean will always increase of decrease

What changes about the Mode when you remove the outlier

It never changes

Stratified Sampling Allocation formula

Sample size of subgroup=specific subgroup population/entire population*target size for your final sample

Simple expansion estimation formula

population version=fraction*population

Systematic sampling interval

Sampling interval=total population size/desired sample size

What is a census

In a census, data is collected from every member of a population.

What is a sample

A sample survey is instead done on a subset of the population

Random sampling

A sample is formed by selecting items from the population at random. All the items have an equal chance of being selected

Systematic sampling

a starting point is chosen at random, and then items are chosen at regular intervals

Stratified sampling

Stratification is the process of dividing a group into subgroups with the same characteristics before we draw our random sample

Sampling Bias (Selection Bias)

Occurs when the sampling method systematically favors certain parts of the population, leaving others over-represented or under-represented

Undercoverage (Bias)

Happens when a portion of the population is completely left out or inadequately represented in the sample frame

Voluntary Response Bias

Arises when individuals can choose on their own whether to participate in a survey. Results usually capture only people with strong (often extreme) opinions

Nonresponse Bias

Occurs when individuals chosen for a sample fail or refuse to respond, and their opinions differ systematically from those who did respond

Convenience Sampling (Bias)

Choosing a sample based on who is easiest or most accessible to reach rather than using random selection