---
title: "PSY392_HW4"
output: html_document
---

Please read everything carefully!!!

*** Submit this R markdown file but change the name of the file to lastName_FirstName_PSY392_HW4.rmd

*** Submitting an incorrect file type or a poorly labeled HW (e.g., HW3) will result in a 2 point deduction


# Question 1
Why is alpha important?


# Question 2
What is the formula for computing a t statistic?


# Question 3
How does increasing the sample mean affect the t value?


# Question 4
How does increasing the sample mean affect the t value?


# Question 5
How does decreasing the sample size affect the t value?


# Question 6
How does increasing the standard deviation affect the t value?


# Question 7
What is power?


# Question 8
What can be done to increase power?


# Use the Multiple Testing code that has covered on 10-2 to answer questions 9 and 10

# Question 9
What happens to the probability of getting at least one significant test if the number of populations increases?


# Question 10
How can alpha be modified to account for multiple hypothesis tests?




# Question 11
Using the mtcars data set that comes with R, compute a t value compairing the mpg for 4 and 6 cylinder cars.
Hint, the data set has three types of cylinders so you will need to split or subset the data as a t test is for comparing only two means.
You did this in project 6 in STAT 190.
```{r}
data <- mtcars # store mtcars as a data frame called data
view(data) # look at data 
names(data) # get the column names
levels(as.factor(data$cyl)) # there are three types of cylinders in this data set

# hints
?t.test
?split
?subset
```