Random Sampling
If your sample is not randomly selected, then this is introduced, which may influence the study in favor of one outcome over other outcomes
Bias
Do you support funding research on alternative energy sources to reduce our reliance on high-polluting fossil fuels?
Leading Question
A class of 30 students are testing how two different textbooks effect students scores. After a month of work students are given a quiz.
Assign each student a number from 1 to 30. Randomly generate 15 non-repeating numbers and those 15 students receive one textbook while the other 15 receive the other. Compare the quiz scores of each group.
Completely randomized design
What is the mode for the following data?
Red-7, Orange-4, Yellow-2, Green-6, Blue-9, Purple-2
Mode=Blue
Almost all of the data lies within ________ above or below the mean.
3 standard deviations
A sampling method where every member of a population to have an equal chance of being selected. IE everyone's names are in a hat and 5 are pulled out and chosen for the sample.
Simple Random Sampling
How many AP classes will you complete by the end of your high school career?
_0-4
_4-8
_8-12
_12+
Repeated Choice Bias
A restaurant owner wants to know does background music affect how long customers stay. Does the time of day?
The owner separates customers into blocks based on lunch or dinner customers. Within each time block tables are randomly assigned to listen to soft jazz or no music. The owner recorded how long customers stayed at their tables.
Randomized Block Design
What are the relative frequencies of Purple and Orange given the following frequencies?
Red-7, Orange-4, Yellow-2, Green-6, Blue-9, Purple-2
Purple-2/30=6.67%
Orange-4/30=13.33%
The running times of athletes are normally distributed with a mean of 12 seconds and a standard deviation of 0.5 seconds. About what percent of athletes run between 11.5 seconds and 12.5 seconds?
68%
A sampling method where you divide the population into homogenous groups. IE Students are divided by graduating class and then 7 students are chosen from each grade.
Stratified Random Sampling
A history teacher samples their first period class to represent all students at their school.
Convenience Sample
A phone company wants to test which keyboard layout allows people to type faster. Each participant types the same paragraph twice: once using Keyboard A, once using Keyboard B. The order of the keyboards is randomized for each participant. The phone company compares each person's typing speeds for the different layouts.
Matched Pairs Design
What is the mean for the following data?
3,8,7,6,9,4,15,3,9,6,8,7,9,5,7,3,2,8
Mean=6.61
The weights of apples are normally distributed with a mean of 150g and a standard deviation of 10g. About what percent of apples weigh more than 160g?
16%
A sampling method where there is a rule used to select a sample. IE every fourth student to walk through the door.
Systematic Random Sampling
A grocery store prints survey codes at the end of every receipt. They do not receive responses from every customer, but works off of the responses provided.
Volunteer Response Sample
A sports trainer wants to determine whether a new energy drink improves athletes' reaction times. Each athlete will drink the new energy drink on one day and a placebo drink that looks the same on another day. The order of the drinks is randomly assigned.
Matched Pairs Design
What is the best measure of center for the following data? Why?
3,8,7,6,9,4,25,3,9,6,8,7,9,5,7,3,2,8
Median, since there is an outlier
The lifespan of batteries are normally distributed with a mean of 100 hours and a standard deviation of 15 hours. About what percent of batteries last between 85 and 130 hours?
81.5%
A sampling method where you divide the population into random (heterogeneous) groups. IE A lunch students are split into groups: 1,2,3,4,5. Three random groups are selected
Cluster Random Sampling
Why are there significantly more firemen than firewomen?
Loaded Question
A farmer wants to test which fertilizer helps plants grow taller. Since different parts of the fields get different amounts of sunlight, the fields are divided into sunny areas and shady areas. Within each area, the farmer randomly assigns some plants to receive standard fertilizer and others to receive organic fertilizer. After a couple of weeks the farmer measures the height of the plants.
Randomized Block Design
Are there any outliers in the following data? If so, what are they?
SHOW YOUR WORK
75,76,75,72,72,72,71,74,78,78,72,73,75,72,76,79,71,72,71,72,74,70,72,70,72,73,74,72,79,76,72,71,71,64,72,97,76,75
Standard Deviation is 4.81
Yes, 97 is an outlier since it is greater than the upper bound at 83.46.
The weights of packages shipped by a company are normally distributed with a mean of 50 lbs and a standard deviation of 6 lbs. What is a range of weights that contains 47.5% of the data?
38-50
50-62