HL IB Math U5

Discrete Data

Certain number of values possible, countable

Continuous Data

Take on any value, usually measured

how can Reliability be compromised

missing data, small sample size, error in handing data

target population

population from which you want to take a sample.
celery sticks grown in a US state

sampling frame

list of the items or people (within the target population) from which you can take your sample.

list of celery sticks

sampling unit

single member (such as an item or person) from the sampling frame that is chosen to be sampled.

one celery stick

sampling variable

the variable under investigation. This is the characteristic that you want to measure from each sampling unit.

length of celery stick

sampling values

the possible values which the sampling variable can take.

measured length of celery stick

Simple random sampling (SRS)

Each member of the population has an equal chance of being selected. A sample is chosen by drawing names from a hat, or assigning numbers to the population and using a random number generator.
Example: To conduct a simple random sample to find the mean length of time spent doing homework, you might put the names of every student in the school into a hat and draw out the names of 100 students to form a sample.

Systematic sampling

Here, you list the members of the population and select a sample according to a random starting point and a fixed interval.
Example: If you wanted to create a systematic sample of 100 students at a school with an enrolled population of 1000, you would choose every tenth person from the list of all students.

Stratified sampling

This involves dividing the population into non-overlapping smaller groups known as strata. The strata are formed based on members' shared characteristics. You then choose a random sample from each strata, and put them together to form your sample.
Example: In a high school of 1000 students, you could choose 25 students from each of the four year groups to form a sample of 100 students.

Quota sampling

This is like stratified sampling, but involves taking a sample size from each strata in proportion to the size of the population. *NOT RANDOM
Example: In a high school of 1000 students where 60% are female and 40% are male, your sample should also have 60% female and 40% male.

Convenience Sampling

most accessible, online survey etc.

Mean

average

mode

most frequent

median

middle value

How to find low outliers

LOW OUTLIERS < Q1 - 1.5(IQR)

How to find high outliers

HIGH OUTLIERS < Q3 + 1.5(IQR)

IQR FORMULAS

Q3 - Q1 = IQR

CSOS

Center(mean,median,mode), spread(range, min,max), outliers, shape

Type of shapes of graphs