Unit 3 IP AMDM
APPLIED MANAGERIAL DECISION-MAKING
MGMT 600
CHAT 3: BASICS OF RESEARCH
SESSION: 1701A-02
AGENDA
- Hypothesis: Null vs. Alternative
- Testing for validity
Nonparametric and Parametric tests
Chi-square tests
- Revising Probability estimates
THE HYPOTHESIS
- All research starts with a __________ – the research question.
- The basis of the research question is a hypothesis: this is what we are trying to determine through our sampling, testing or study.
Null Hypothesis
The null hypothesis, ____, is the commonly accepted fact. Researchers work to reject, nullify or disprove the null hypothesis. Researchers come up with an alternate hypothesis, one that they think explains a phenomenon, and then work to ___________________
*
THE HYPOTHESIS
- The Null Hypothesis is tested against the Alternative Hypothesis
Alternative Hypothesis
The alternative hypothesis, ____, is the hypothesis used in hypothesis testing that is contrary to the null hypothesis. It is usually taken to be that the observations are the result of a real effect (with some amount of chance variation superposed).
*
THE HYPOTHESIS
- Why Do I need to Test it? Why not just prove an alternate one?
- The short answer is, as a scientist, you are ________ to; It’s part of the scientific process. Science uses a battery of processes to prove or disprove theories, making sure than any new hypothesis has no flaws. Including both a null and an alternate hypothesis is one safeguard to ensure your research isn’t flawed. Not including the null hypothesis in your research is considered very bad practice by the scientific community. If you set out to prove an alternate hypothesis without considering it, you are likely setting yourself up for failure. At a minimum, your experiment will likely not be taken seriously.
*
THE HYPOTHESIS
Example:
- Not so long ago, people believed that the world was flat.
- Null hypothesis, H0: The world is flat.
- Alternate hypothesis H1: The world is round.
*
THE HYPOTHESIS
Example:
- Several scientists, including Copernicus, set out to disprove the null hypothesis. This eventually led to the rejection of the null and the acceptance of the alternate. Most people accepted it — the ones that didn’t created the Flat Earth Society!. What would have happened if Copernicus had not disproved the it and merely proved the alternate? No one would have listened to him. In order to change people’s thinking, he first had to prove that their thinking was wrong.
*
THE RESEARCH
- Set your Null / Alternative hypothesis
- Conduct study / Gather data
- Analysis and test data
“Am I statistically valid”
*
THE RESEARCH
First a word from our sponsor: the average
From a population we want to know how our null or alternative represents the whole – and we use _______ in one of three contexts.
*
THE RESEARCH
_______ – The "mean" is the "average" you're used to, where you add up all the numbers and then divide by the number of numbers
1 2 5 1 3 4 5 3 3 3 3 5 1 2 3 5 4 5 = 58 or a mean of 3
________ – is the "middle" value in the list of numbers. To find the median, your numbers have to be listed in numerical order from smallest to largest, so you may have to rewrite your list before you can find the median
1 1 2 4 4 4 4 5 5 5 6 6 6 7 7 8 9 10 = median of 5
_______ - The "mode" is the value that occurs most often. If no number in the list is repeated, then there is no mode for the list.
1 2 5 1 3 4 5 3 3 3 3 5 1 2 3 5 4 5 = 58 or a mode of 3
*
THE RESEARCH
Two types of testing: ___________ and ___________
___________ – used to test group means
work well with skewed or non-normal distributions
Can work well when spread of each group is different
have more statistical power than nonparametric
More likely to detect a result
*
THE RESEARCH
Two types of testing: Nonparametric and Parametric
____________ – used to test group medians
Measures the central tendency
Works well even with a small sample size
Can test ordinal, ranked or data with outliers
*
THE RESEARCH
Then there is Chi-square ___________ of fit testing:
- The Chi-square test is intended to test how likely it is that an observed distribution is due to chance. It is also called a "goodness of fit" statistic, because it measures how well the observed distribution of data fits with the distribution that is expected if the variables are independent.
- A Chi-square test is designed to analyze _________ data. That means that the data has been counted and divided into categories. It will not work with ___________ or continuous data (such as height in inches).
*
THE RESEARCH
Examples of Chi-square goodness of fit testing:
- For example, if you want to test whether attending class influences how students perform on an exam, using test scores (from 0-100) as data would not be appropriate for a Chi-square test. However, arranging students into the categories "Pass" and "Fail" would. Additionally, the data in a Chi-square grid should not be in the form of percentages, or anything other than frequency (count) data. Thus, by dividing a class of 54 into groups according to whether they attended class and whether they passed the exam, you might construct a data set like this:
*
HOW TO USE CHI-SQUARE
Key components of chi-square
What makes it valid
When do you accept or reject the null
Why is chi-square called “best-fit” analysis
THE RESEARCH
And just because we need a laugh:
*
PROBABILITY ESTIMATES
We deal with probability estimates all the time. Weather, stocks, health, elections, markets, ect.
So, how many of you would take an umbrella to work if got up tomorrow and weather report had a prediction of a 35% chance of rain?
What if that was a 25% increase from the night before?
What if that was a 25% decrease from the night before?
*
PROBABILITY ESTIMATES
Study by Maglio and Polman.
People experience probabilities as a psychological distance.
The higher the probability the closer and more significant the event.
Their test
How Changing Predictions Affect our Decision-Making by Nathan Collins
*
PROBABILITY ESTIMATES
Implications ?
How Changing Predictions Affect our Decision-Making by Nathan Collins
*