Cheatography

# AP Statistics Unit 3 Cheat Sheet by kayheartsuu

AP Statistics Unit 3 Study Guide

### Simula­tions Terms

 simulation the imitation of chance behavior, based on a model that accurately reflects the experiment under consid­eration stopping rule "­con­tinue selecting until ..."

### How to Write Simulation Descri­ption

 1. Select __ digit numbers to represent __. 2. Let __ - __ represent ___ and let __ - __ represent ___. 3. Select __ or Continue selecting ___ until ___. 4. Record ___. 5. Trial One : ___ ; Trial Two : ___ ; Trial Three : ___

### Simulation Example

 Alex needs a blood transf­usion. She needs to find someone with B+ blood or she will die. 9% of all people have B+ blood. How many people on average would you need to check the blood type of until you find someone who can save Alex's life? 1. Select 2-digit numbers to represent people 2. Let 00-08 represent people with B+ blood and 09-99 represent people without B+ blood 3. Continue selecting people until you find someone with B+ blood 4. Record how many people you select before you find someone with B+ blood 5. Trial One:6 ; Trial Two:16 ; Trial Three:15

### Sampling Design Example

 a college professor wants to survey a sample of students taking her large lecture course. There are about 150 students in the course, and 10 of those students are graduate students. She wants to take a systematic random sample of approx­imately 30 students. Which strategy will accomplish her intended design? randomly select one of the first 5 students to arrive to class, and every 5th student thereafter to take the survey.

### Biases

 bias a systematic error in measuring the estimate that would repeatedly cause the data to be wrong voluntary response bias people select themselves to partic­ipate in the study nonres­ponse bias indivi­duals who are randomly chosen for the sample cant be contacted or refuse to cooperate conven­ience sampling asking people who are easy to ask; convenient but not random under coverage bias some groups are left out of the selection process response bias the behavior of the respondent or interv­iewers causes you to get incorrect answers wording bias when wording of the question influences the answers that are given

### Bias Examples

 voluntary bias online polls, facebook questi­onn­aires nonres­ponse bias mailed polls, new apps on phone conven­ience bias friendly looking people, all people at the park under coverage bias only your neighb­orhood, phone books response bias cosplayer asking if people think cosplay is weird wording using strong vocabulary

### Sampling Design Terms

 population the entire group of indivi­duals we want inform­ation about census a complete count of the popula­tion; when you gather general inform­ation about the entire population sample a part of the population we actually examine in order to gather inform­ation sampling design the method used to choose the sample from the population sampling frame a list of every individual in the population simple random sample every individual has an equal chance of being chosen stratified random sample population is divided into strata and then simple random sample is used on each stratum systematic random sample randomly select a number between one and n and survey every nth person after that cluster random sample randomly pick a location and sample all from that location multistage sample a combin­ation of different sampling techniques

### How to Describe Sampling Design

 simple random sample put the names/­numbers of all ___ on slips of paper and place in a hat. Mix and randomly draw ___ slips of paper without replac­ement. Survey the corres­ponding people. systematic random sample number all ___ and place ___ numbers in a hat. Mix and randomly select one number and survey the corres­ponding person. Survey every nth person on the list after that. cluster random design number all clusters and put the numbers into a hat Mix and randomly select a number from the hat. Survey everyone in that cluster. stratified random sample sort everyone into strata then number ___ in all the stratum. place the numbers in a hat and draw __ numbers. survey the corres­ponding people in that specific stratum. repeat the process for all strata

### Experi­mental Design Types

 completely randomized design experi­mental units are assigned completely at random to treatments randomized block design experi­mental units are blocked in homoge­neous groups and then randomly assigned to treatments matched pairs design a special type of block design; match up experi­mental unit according to similar charac­ter­istics and randomly assign one to treatment A and the other get treatment B automa­tically

### Experi­mental Design Terms

 observ­ational study observe outcomes without imposing any treatment experiment actively impose a randomly assigned treatment in order to observe the response experi­mental unit the single individual to which the different treatments are randomly assigned factor / explan­atory variable what we test or what we change level a specific value or type for the factor response variable what you measure or record at the end of the experiment treatment a specific experi­mental condition applied to the units control group a group that is used to compare the factor against; can be placebo placebo a "­dum­my" treatment that can have no physical effect; not required in every experiment blinding method used so that units or evaluators do not know which treatment units are getting double blinding neither the units nor the evaluators know which treatment a subject recieved confou­nding variable a third variable that potent­ially affects both the factor and the response variable

### Three Principles of Experi­mental Design

 control the effects of extraneous variables on the response random­ization used to assign subjects to treatments replic­ation of the experiment on many subjects to quantify the natural variation in the experiment

### Experiment Example

 A consumer group wants to test cake pans to see which works the best. It will test aluminum, glass, and plastic pans in both gas and electric ovens experi­mental unit: cake batter factors: material of pan & type of oven levels: aluminum, glass, or plastic & gas or electric response variable: evenness of cake amount of treatm­ents: six