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Want to see how much you have been learning?
Want to see how much you have been learning?
Drop by and get some practices before your DS 123 final!
Drop by and get some practices before your DS 123 final!
Our Content
Our Content
February 2018 Monthly Project!
This video helps to explain a variety of symbols that you will see in your course. Give it a watch, take some notes, and come see us in the Learning Center if you have any questions!
Helpful videos we've found online!
Helpful videos we've found online!
Chi-square tests are pretty different than any other test we work with in DS123. This video works through a problem, and gives good explanations along the way. Just make sure you refresh yourselves on the difference between p-values and alphas, and test statistics and critical values before watching this.
Here's a really thorough explanation of Goodness of Fit. And, if you've ever wondered what degrees of freedom really are, he explains that too!
Watch this Crash Course video for some helpful tips for studying. We love the notecard tip!
Shared by Emilee Silveira
This video is helpful to walk you through Hypothesis Testing. But be warned-- he uses a different method for writing the null hypothesis than most of our professors would, and we generally assume conditions are good enough to test.
Shared by Emilee Silveira
An introductory video for One-way ANOVA.
Need a refresher on why we learn about statistics? Watch this!
Shared by Emilee Silveira (1/25/18)
If you need a refresher on z-scores and probability, please watch this video.
Having trouble with F-Tests? Take a look at this video!
Is linear regression just not clicking? Try watching this.
Other Assorted Tips
Other Assorted Tips
How strong is the correlation? Is the correlation positive or negative?
Need some guidance on Type 1 and Type 2 errors? Check out the matrix and example scenario below!
The z-score is one of the most important formulas you will learn.
Need help differentiating between mean and proportion, or the symbols for populations versus samples? This resource will help break it down!
Larger samples lead to more precise estimates, resulting in narrower confidence intervals, while smaller samples create more variability, leading to wider intervals.
POSITIVE Z-SCORE
NEGATIVE Z-SCORE
T-TEST TABLE
One-Way versus Two-Way ANOVA
Quick Question Guide
Ask these questions:
How many independent variables (factors) are there?
Just one? → One-Way ANOVA
Two? → Go to #2
Is each group combination measured more than once?
Only once? Two-Way ANOVA without replication
More than once? → Two-Way ANOVA with replication
Hypothesis Testing
Decision Sciences 123 Review
Hypothesis testing is the fundamental structure in which all problems in DS-123 utilize.
There are always two steps in beginning any problem in DS-123:
Specify population parameter of interest
State the null & alternative hypothesis
What are the possible population parameters of interest? (This is a question that your professor asks every worksheet!)
Population parameter of interest is found in your worksheet problem!
It is the “crux” of the problem, the portion that makes it unique from other types of problems. It identifies what calculations, formulas, and steps you need to take to solve it.
In Hypothesis Testing some of the most common population parameters of interest are Population Mean = µ and Population Proportion = π
Example: Assuming the sample proportion is 15%, what is the approximate probability that more than 10% of the sample would report that they experienced extreme levels of stress during the past month?
Similar to the population parameter of interest, the null & alternative hypothesis is located within your word problem, if not directly equated.
Ex. A local skate park is considering closing a public restroom if it is true that fewer than 4 people use it per day.
Null: H0: μ≥4
Alternative: Ha<4
Did you notice the relationship between the wording of the problem and the alternative hypothesis? They match!
This is because the null hypothesis is always the status quo, or the “nothing is happening” hypothesis. The null hypothesis is what you are “testing” but really the alternative hypothesis exists as the opposite of the null hypothesis. Take special care to practice identifying null and alternative hypotheses from a variety of different hypothesis testing problems.
Wrong Page? Back to Decision Science homepage: Decision Science
Memes to brighten your day :)
Memes to brighten your day :)
P < 0.05 (or whatever your alpha is) means reject the null hypothesis!
Shared by Emilee Silveira
....It can be fun! I swear!!!!
Shared by Emilee Silveira
ANOVAs can be so confusing! If you're having trouble keeping everything straight, we can help.
Then it's all ANOVA.
Gotta love them!
If there's 3 or more means, do an ANOVA!
Multiple regressions are awesome, because you can use them to predict the future! You can assess different factors and make an equation to predict, for example, total sales in two months. They are extremely useful to business people for this reason. Make sure you understand it conceptually.
Shared by Emilee Silveira
If you're lost, come to tutoring for help! There is no such thing as a dumb question.
If you're getting frustrated by all the different ways to hypothesis test, come see us for help!
Shared by Emilee Silveira (1/25/18)
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