Show:
Samples and Bias
So You Think You Know Experiments?
So You Know Experiments?
Inferencing
What's Up?
100
Identify the sample and the population: A high school student newspaper plans to survey 150 local businesses at random. 73 return the questionnaire.
All local business- population 73 that return - sample
100
In this type of design the experimental units are assigned to the treatments completely by chance. What is is called?
What is completely randomized design?
100
Describe the main difference in the design of observational studies and experiments.
What are imposed treatments on individuals to prevent confounding in experiments?
100
If we have randomly selected the individuals and randomly assigned the individuals to groups, may we infer about the population and cause and effect?
What is yes?
100
True or false: in a table of random digits, each pair of digits has 1/100 of being 00.
What is true?
200
A random sample of the population is surveyed and asked "Should we continue to destroy our habitat or find new ways to preserve energy and increase productivity?" Explain the bias found.
Wording of question bias
200
Hayden is testing how well pine trees of Arizona grow in the shade. He planted pine seedlings in a greenhouse in either full light, light reduced to 25%, or light reduced to 5% normal. At the end of his study, he dried the trees and weighted them. Identify the explanatory and response variables and the treatments.
What are pine seedings? What are light intensity and dry weight at the end of the study? What are full light, 25% of the light, and 5% of the light?
200
In this design of experiment, there is random assignments of experimental units to treatments is carried out separately within each block. Identify this type of design.
What is a randomized block experiment?
200
Explain the difference between the types of inference that can be made as a result of random sampling and random assignment.
What is if a study involved random sampling, we can make inferences about the population from which we sampled. If the study involved random assignment, we can make inferences about cause and effect.
200
What is a double blind experiment
What is an experiment in which neither the subject or experimenter knows the treatment prescribed
300
Laurynn created an online poll to ask the following question:"Should women be paid the same amount as men for the work they do?" Her results were the following: 32% no, 68% yes. What type of survey did Laurynn create?
What is voluntary response?
300
You use this to prevent confounding and reduce variability in the response variables. What are you using?
What is a control group?
300
What does statistically significant mean for any scenario?
What is the observed effect is so large that it would rarely occur by chance?
300
Define statistically significant
What is creating a difference so big that it can't be ascribed to chance variation in random assignment
300
Describe the placebo effect
What is individuals exhibiting effects of a treatment even when it's not prescribed
400
Alex designed a survey to determine how much sleep students get. To make data collection easier, she surveyed the first 100 students that arrived to school. What type of sample did she use and how does this lead to bias?
Convenience sample The students most likely get less sleep than those that arrive later.
400
Describe the difference between a cluster and strata
What is Cluster- different within, Same between Strata- same within, different between
400
The idea of this design is to create blocks by matching pairs of similar experimental units. Then you use chance to decide which member of pair gets the first treatment. Identify this type of design.
What is a matched pair design?
400
Hayden would like to see if children in foster homes do better than similar children placed in an institution. He found that the answer is a clear yes. The subjects were 238 young children abandoned at birth and living in orphanages in Valencia, Spain. Half of the children were chosen at random and placed in foster homes. The half were in orphanages. What conclusion can we draw from this study?
What is we can infer that the difference between foster care or institutional care caused the difference?
400
Consider an experiment to investigate the effectiveness of different insecticides in controlling pests and their impact on the productivity of tomato plants. True or false: the best reason for randomly assigning treatment levels (spraying or not spraying) to the experimental units is the random assignment will tend to average out all other uncontrolled factors such as soil fertility so that they are not confounded with the treatment effects.
What is true?
500
What is the difference between under coverage and non Response?
Under coverage cannot be chosen in a sample. Non response is when they can't be contacted or refuse to participate
500
You use enough experimental units in each group so that any differences in the effects of the treatments can be distinguished from chance difference between the groups. What are you doing?
What is replication?
500
Laurynn hears that an exercise plan will help dancing more than dancing. She is eager to show her dance team. She decides to let her team which if the two treatments they will under go for 14 weeks- dancing or using the exercise plan. She will use the number of awards a girl can do at the end of the experiments as the response variable. Which principle of experimental design did Laurynn violate?
What is random assignment?
500
If we randomly select individuals but do not randomly assign them to groups, what may me infer about?
What is only the population?
500
When names of individuals are not known
What is anonymity?