Activity!Get your heart beating!

• Are standing pulse rates generally higher than sitting pulse rates?

• We will preform two experiments to try to answer the question!

• 1) Completely Randomized design– Hat method – 1 stand, 2 sit– Count pulse for 60 seconds. BPM.– Plot on dot plot (one above the other)

Activity!Get your heart beating!

• 2) Matched Pairs Design– Now take the pulse of the other condition– Take the difference: – Make dot plot of differences (sign matters!)

Analysis• We look at the dot plot of a Completely random

design and cant necessarily say there is a significant difference between standing and sitting

• We look at the dot plot from a matched pairs and ___ out of ___ record a positive difference (meaning standing pulse was higher). These data provide strong evidence that people’s standing pulse rates tend to be higher than their sitting pulse rates.

Using Studies Wisely:Ethics behind Experiments

Section 4.3

Reference Text:The Practice of Statistics, Fourth Edition.

Starnes, Yates, Moore

Objectives

• Ethical claims about population based on Sample

• Challenges of establishing causation• Criteria for causation for not doing

experiments• Data ethics- “First, do no harm”

Scope of Inference• Random sampling avoids bias and produces

trustworthy estimates of the truth about the population– Survey: random selection allows an

inference about the population– Experiment: random assignment of

individuals to groups make an inference about the cause and effect• Since the experiment used volunteer subjects, this limits

scientists’ ability to generalize their findings to some larger population of individuals

Challenges for establishing Causation

• The serious threat is that the treatments, the subjects, or the environment of our experiment may not be realistic

• Lack of realism can limit our ability to apply the conclusions of an experiment to the settings of greatest interest.

Example

• Animal testing and lack of realism – When new products are being developed for

use by humans, the products are often tested on animals first. While animals share some physiological features with humans, they are not the same, and we should always be cautious when applying the results of tests on animals to humans.

Not practical, and not ethical

• Consider these important questions:– Does texting while driving increase the risk of

having an accident?– Does going to church regularly help people

live longer?– Does smoking cause lung cancer?

• We cant randomly assign anyone to text while driving nor any others, not to mention the ethics behind it.

Criteria for establishing causation w/o experiments

• It is sometimes possible to build a strong case for causation in the absence of experiments.

• The evidence that smoking causes lung cancer is about as strong as nonexperimental evidence can be!

• What is the criteria to make that claim?

Criteria for establishing causation w/o experiments

• The association is strong– The association between smoking and lung

cancer is very strong• The association is consistent

– Many students of different kinds of people in many countries link smoking to lung cancer. Reduces chances of lurking variables for geographical locations.

Criteria for establishing causation w/o experiments

• Larger values of the explanatory variable are associated with stronger responses– People who smoke more cigarettes per day or

who smoke over a longer period of time get lung cancer more often.

• The alleged causes precedes the effect in time– Lung cancer develops after years of smoking.

Number of men dying from cancer rose as smoking became more common.

Criteria for establishing causation w/o experiments

• The alleged cause is plausible– Experiments with animals show that tars from

cigarette smoke do cause cancer.

• Hence the Surgeon General Warning!

Data Ethics

• Medical professionals are taught to follow the basic principal “First, do no harm.”

• Shouldn't those who carry out statistical studies follow the same principals?– Not always as simple as it sounds….Read the following situations and decide if you think each of the following is ethical or unethical…

Example 1

• A promising new drug has been developed for treating cancer in humans. Before giving the drug to human subjects, researchers want to administer the drug to animals to see if there is any potentially serious side effects.

Example 2• Are companies discriminating against some

individuals in the hiring process? To find out, researchers prepare several equivalent resumes for fictitious job applicants, with the only difference being the gender of the applicant. They send the fake resumes to companies advertising positions and keep track of the number of males and females who are contacted for interviews.

Example 3• In a medical study of a new drug for migraine

sufferers, volunteer subjects are randomly assigned to two groups. Members of the first group are given a placebo pill. Subjects in the second group are given the new drug. None of the subjects know whether they are taking a placebo or the active drug. Neither do any of the physicians who are interacting with the subjects.

Example 4

• Will people try to stop someone from driving drunk? A television news program hires an actor to play a drunk driver and uses a hidden camera to record the behavior of individuals who encounter the driver

Basic Data Ethics

• The most complex issues of data ethics arise when we collect data from people. Here are some basic standards of data ethics that must be obeyed by all studies that gather data from human subjects, both observational studies and experiments….

Basic Data Ethics• All planned studies must be reviewed in advance

by an institutional review board charged with protecting the safety and well-being of the subjects.

• All individuals who are subjects in the study must give their informed consent before data are collected

• All individual data must be kept confidential. Only statistical summaries for group of subjects may be made public.

Objectives

• Ethical claims about population based on Sample

• Challenges of establishing causation• Criteria for causation for not doing

experiments• Data ethics- “First, do no harm”

Homework

Check for Understanding Packet for 4.1,4.2, 4.3Continue working on Chapter 4 Reading Guide.