This course, classroom can be divided into describe (classroom) and inference statistics.
wiki
Completed in 2017/08/07

Orientation!

Course Wiki

You can get to the course wiki by clicking “Materials” or following this link.

Intro to Research Methods

Memory Test Description

Here is a brief description of how the test worked, to help you follow the rest of the lesson. The test consisted of three parts:

Users were shown 12 photos in the first part.
Users were shown another 12 photos in the second part.
Users were shown 48 photos in the third part and asked if they saw each photo
in the first part, the second part, or neither.

After the test, users were given two scores:

A “Recognition score”, calculated as the percentage of times they correctly identified whether they saw the face at all, regardless of which part the face was from.
A “Temporal memory score”, calculated as the percentage of recognized faces that were identified with the correct part (part 1 or part 2).

Users were advised to take a 5 minute break between each part of the test.

Quiz: Control for Time of Day

lurking variables
extraneous factor

Quiz: Same Scores

Population parameters (such as mu, or μ) are values that describe the entire population. Sample statistics (such as X-bar, or $\bar{x}$​​ ) are values that describe our sample; we use statistics to estimate the population parameters. Estimates are our best guesses for the population parameters. So, for example, we would use X-bar to estimate mu.

Quiz: Katie's Hand

Click this link to access the data: Height and hand length

Copy and paste the data into your own spreadsheet to create the scatterplot. From Google Drive (at the top of the page once you’re signed in to your Google account), click the button on the left that says “CREATE” and click “Spreadsheet.”

Conclusion

construct
opertaional definition
independent variable
dependent variable
extraneous or lurking variable
experimental study - casual conclusion
observational study

Visualizing Data

Quiz: Number of Rows

interval = bin = bucket

Different Bin Sizes

Click this link to play around with the histogram applet! (You may need to install the Java plug-in.) Interactivate Histogram Applet

Udacity Student Ages Data: Make sure you have one number per line for the applet.

Quiz: Difference Between Graphs

histogram: bin x-axis: numerical/quantitative
bar: x-axis: categorical/qualitative

Problem Set 2: Visualizing data

Quiz: 1. Blood Types

The Σ symbol means the total sum. It is the Greek letter capital sigma. f stands for frequency (count), p stands for proportion.

The Σ symbol means the total sum. It is the Greek letter capital sigma. f stands for frequency (count), p stands for proportion.

Enter each answer as a number without any special characters, including % signs. Enter proportions as decimals.

The Σ symbol means the total sum. It is the Greek letter capital sigma.

Quiz: 31. Skewness

positively skewed

Tutorial

Copy and paste the data into your own spreadsheet to perform the calculations. From Google Drive (at the top of the page once you’re signed in to your Google account), click the button on the left that says “CREATE” and click “Spreadsheet.”

You will work with this data in Lesson 3.

Central tendency

Quiz: Mode of Dataset

mode: most frequency

mean median mode

Problem Set 3: Central tendency

Quiz: 1. BBC Memory Scores

Copy and paste the data into your own spreadsheet to perform the calculations. From Google Drive (at the top of the page once you’re signed in to your Google account), click the button on the left that says “CREATE” and click “Spreadsheet.”

Deal or No Deal?

Quiz: 20. NHL (Mean)

Round to the nearest hundredth (xx.xx)

National Hockey League

Variability

quartile

IQR=Q3-Q1

< Q1 - 1.5 IQR
> Q3 + 1.5 IQR

variance

Standard Deviation

square root of variance

Quiz: SD in Words

Copy and paste the data into your own spreadsheet to perform the calculations. From Google Drive (at the top of the page once you’re signed in to your Google account), click the button on the left that says “CREATE” and click “Spreadsheet.”

Quiz: Find df

df = 1 = Number of categories - 1

Quiz: Calculate p

P value equals 0.0891
Not significant at either level

The instructor should have said, “Calculate the one-tailed p-value.” GraphPad’s Chi-Square calculator reports the p-value as two-sided, but should be taken as the one-sided p-value we desire.

Quiz: Remember Details

Elizabeth Loftus: Eyewitness Testimony

Source: Loftus, E.F. & Palmer, J.C. (1974). Reconstruction of automobile destruction: An example of the interaction between language and memory. Journal of Verbal Learning and Verbal Behavior. 13, 585-589.

Quiz: Broken Glass

Hit Smashed Control Total
Yes 7 16 6 29
No 43 34 44 121
Total 50 50 50 150

Null Hypothesis: Student’s response for whether or not they saw broken glass is independent of the wording used in question
Expected frequencies:
For (Yes, Hit) is (29/150) * 50
For (No, Hit) is (121/150) * 50

Quiz: Degrees of Freedom

df = 2 = (number of rows - 1)(number of columns - 1)

Quiz: Effect Size

Chi-square Test for Independence
$$Cramer’s V (\phi_c) = \sqrt{\frac{\chi^2}{n(k - 1)}}$$
k: smaller of number of rows or columns (2)
n: total number (150)

Assumptions and Restrictions

Avoid dependent observations
Avoid small expected frequencies (large n)

Problem Set 16: Chi-Squared tests

Ranking

Ordinal

help

Nominal

time

ratio

error

ratio

not

Quiz: 12. Which χ^2 Test?

outcome frequencies expected frequencies
1 8 4
2 4 4
3 1 4
4 8 4
5 3 4
6 0 4

good nominal

5

Quiz: 18. Null Hypothesis

Cabin Steerage Total
Yes 299 186 485
No 280 526 806
Total 579 712 1291

independent

Quiz: 19. Which χ^2 Test?

Indenpence nominal

1

0.3/15

120*0.02+5.24

Final Project

Final project details can be found [here](https://www.udacity.com/wiki/ud201/final_project.

Here are helpful tips and suggestions as you work on your final project!