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# DS with R | Mar 31 - Apr 22 | Samridhi

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#### Priyanka_Mehta

##### Well-Known Member
Simplilearn Support
Hello All,

Greetings from Simplilearn!!

Let us have a discussion about the course, explore the course here and try to resolve all our queries related to the same.

Happy Learning!!

Regards,
Priyanka
GTA - Simplilearn

#### Jyoti_28

##### New Member
Alumni
Hi Priyanka,

There are 4 projects in DS with R. I was going through project descriptions. Do we know when to start working on project. Which lesson will cover which project#. Or After going through how many lessons we can start project.

#### Priyanka_Mehta

##### Well-Known Member
Simplilearn Support

#### Attachments

• TOC.pdf
60 KB · Views: 38
Last edited by a moderator:

#### Aayush Bhalla

##### Member
Alumni
Question: How many times 1 is occurring in the vector:d = c(1,2,3, 1,3,5,5,2)
Solution:
d = c(1,2,3, 1,3,5,5,2)
count=0
for (val in d){
if(val==1){
count=count+1}
}
print(count)

• Samridhi Dutta

#### _25352

##### Member
Alumni
I am unable to access the Lab it gives - Error :Some error occurred. Please contact customer support.

#### Priyanka_Mehta

##### Well-Known Member
Simplilearn Support
I am unable to access the Lab it gives - Error :Some error occurred. Please contact customer support.
We have forwarded this concern to our team and they are working on the lab issue. It will be resolved within next 24 hours.

• _25352

#### Mudit Agarwal_1

##### Member
Alumni
Q1> count the number of occurrence of 1 in d = c(1,2,3, 1,3,5,5,2)

Solution>
d=c(1,2,3,1,3,5,5,2)
count1=0
for(i in d)
{
if(i==1)
count1=count1+1
}
print("1 occurs in the given array, the following no of times:")
count1

• Samridhi Dutta

#### Mudit Agarwal_1

##### Member
Alumni
Samridhi / Priyanka,

Could you please post the assignment questions here.

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Guys,

Here are the assignment questions:

#Assignment

c(1,2,3, 1,3,5,5,2)
#Find through coding how many times 1 is occurring in the above vector?

#Replicate the output of the following code using while and repeat loop
p=c("Sudhir", "Uma","Manish")
for (i in p)
{
#for each person, print 123
q = c(1,2,3)
for(j in q)
{
r = paste(i, j , sep = "-")

if(r=="Uma-1")
{
break
}
ifelse(r=="Sudhir-2", next, print(r))
}
}

Alumni

#### Kiran Kumar Varanasi

##### Member
Alumni
New
1. Code for Assignment using the While loop is as follows

p=c("Sudhir", "Uma","Manish")
q = c(1,2,3)
i<-1
while(i <= length(p))
{j<-1
while (j <= length(q))
{k <- paste(p,q[j], sep = "-")
if(k=="Uma-1")
{break}
if(k != "Sudhir-2") {print(k)}
j<-j+1
}
i <- i+1
}

2. Code for Assignment using the Repeat Loop

p=c("Uma", "Sudhir","Manish")
q = c(1,2,3)
i <- 1
repeat {j <- 1
repeat {
k <- paste(p,q[j], sep = "-")
if(k=="Uma-1")
{break}
if(k != "Sudhir-2")
{ print(k) }
j<-j+1
if(j>length(q)) {break}
}
i <- i+1
if(i>length(p)) {break}
}

3. For the number of occurence of a number in a variable

z <- c(1,2,3,4,5,4,3,4,5,6,5,4,3,2,3,4,5,6,6,2,3,2,3,1,2,1,4,2,4)
> table(z)
z
1 2 3 4 5 6
3 6 6 7 4 3
Here the number of occurences of each value in the variable z is listed in the second row for the unique value of row one

#11

• Samridhi Dutta

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi guys,

Here are the class notes for Chap-2 and Chap-3 for your reference.

Thank you,
Samridhi

#### Attachments

• Ch2_3_ClassNotes.pdf
355.9 KB · Views: 44

Alumni
Hi Team,

Regards,
Aashish

#### Priyanka_Mehta

##### Well-Known Member
Simplilearn Support
Hi All,

I would like to inform you that the lab issue is resolved now, and you can access R Studio from your LMS account. Kindly try doing doing the same at your end.

Also, please ignore the previous TOC shared, and find the final TOC attached here.

#### Attachments

• Final TOC.pdf
59.9 KB · Views: 23

##### Member
Alumni
Yes, iIwas able to download and ply class 1 the file size is 366 MB

#### _27992

##### Member
Alumni
Hi,

Can you please provide the steps to install R and R Studio on mac OS.

Thanks

#### _27992

##### Member
Alumni
Hi,

R studio in Lab access is not working. I'm getting errors.

#### _26915

##### Richa Rao
Alumni
#Assignment

c(1,2,3, 1,3,5,5,2)
#Find through coding how many times 1 is occurring in the above vector?

#Solution

d = c(1,2,3,1,3,5,5,2)
i=1
count1=0
while(i<=length(d))
{
if(d==1)
{
count1=count1+1
}
i=i+1
}
print(count1)

Last edited:
• Samridhi Dutta

#### _27346

##### Jitendra Kumar
Alumni
#c(1,2,3, 1,3,5,5,2)
#Find through coding how many times 1 is occurring in the above vector?
x=c(1,2,3,1,3,5,5,2)
print(x)
n=0
for(i in x)
{
if(i==1)
n=n+1
else
next
}
print(n)

#Replicate the output of the following code using while loop
p=c("Sudhir","Uma","Manish")
q = c(1,2,3)
a=1
while(a<=3)
{
b=1
while(b<=3)
{r= paste(p[a],b,sep = "-")
if(r=="Uma-1")
{ break
}
if(r!="Sudhir-2")
{
print(r)
}
b=b+1
}
a=a+1
}

#Replicate the output of the following code using repeat loop
p=c("Sudhir","Uma","Manish")
q = c(1,2,3)
a=1
repeat
{
b=1
repeat
{r= paste(p[a],b,sep = "-")
if(r=="Uma-1"||b==4)
{ break
}
if(r!="Sudhir-2")
{
print(r)
}
b=b+1
}
a=a+1
if(a==4)
{
break
}
}

• Samridhi Dutta

Alumni
Trainer

#### daisy.amrita

##### Member
Alumni
Hi Guys,

Here are the assignment questions:

#Assignment

c(1,2,3, 1,3,5,5,2)
#Find through coding how many times 1 is occurring in the above vector?

#Replicate the output of the following code using while and repeat loop
p=c("Sudhir", "Uma","Manish")
for (i in p)
{
#for each person, print 123
q = c(1,2,3)
for(j in q)
{
r = paste(i, j , sep = "-")

if(r=="Uma-1")
{
break
}
ifelse(r=="Sudhir-2", next, print(r))
}
}

Hello Samridhi,

I am unable to run the commands you had mentioned in the class. I've raise a technical ticket on help & support.

Thank you,
Amrita.

#### Aishwarya Deshpande

##### Member
Alumni
Assignment 1:
A <- c(1,2,3,1,3,5,5,2)
x = 0
for(a in A)
{
if(a == 1)
{ x = x+1;
}
}
print (x)

#### Aishwarya Deshpande

##### Member
Alumni
Assignment 2:
p=c("Sudhir", "Uma","Manish")
for (i in p)
{
#for each person, print 123
q = c(1,2,3)
for(j in q)
{
r = paste(i, j , sep = "-")

if(r=="Uma-1")
{
break
}
ifelse(r=="Sudhir-2", next, print(r))
}
}
////////////////Using while Loop//////////
p=c("Sudhir", "Uma","Manish")
i=1
while(i < 4){
q= c(1,2,3)
j=1
while(j<4){
r = paste(p,q[j] , sep = "-")
if(r != "Uma-1" && r != "Uma-2" && r != "Uma-3" && r != "Sudhir-2")
{
print(r)
}
j=j+1
}
i=i+1
}
///////////////////Using Repeat ///////////////////
p=c("Sudhir", "Uma","Manish")
i=1
repeat{
if(i>4){
break
}
else if(i<4){
j=1
repeat{
q=c(1,2,3)
if(j>3){ break}
else{
r = paste(p,q[j] , sep = "-")
if(r != "Uma-1" && r != "Uma-2" && r != "Uma-3" && r != "Sudhir-2")
{
print(r)
}
}
j=j+1
}

}
i=i+1
}

#### daisy.amrita

##### Member
Alumni
Hi Priyanka,

I am still not able to get results in Rstudio as taught by the instructor. Please assist. I do not wish to miss out on activities /working on R in the class today.

#### Aayush Bhalla

##### Member
Alumni
for the sudhir, uma example even I had forgot to k=k+1 and it got stuck in endless loop..how to break the output in that case..it had become endless

Alumni
Trainer
Hi Everybody,

Regards,
Samridhi

#### Attachments

• Class_Notes_07_April.pdf
201.6 KB · Views: 33

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
for the sudhir, uma example even I had forgot to k=k+1 and it got stuck in endless loop..how to break the output in that case..it had become endless
Hi Aayush,

Please click on "stop" on the top of console.

Regards,
Samridhi

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Everyone,

Here are some practice questions for all of you to work upon.

data("iris")
ir = iris

#Q. Find the average sepal length of Setosa species. Hint: use function "mean"

#Q. Find the different categories of species variable. Hint use "table" function on Species variable

#Q. Find which species has the highest Petal Width.

#Q. For all the virginica flowers having petal width = 2.0, make their petal length to 5.5

#--------------------------------------------------------------------------------------------------------------------------------------------------------
#titanic dataset

#Q. Find the number of passengers who survived
#Q. Find the age of Timothy
#Q. Find names of passengers having age>35
#Q. The age of Henry has been entered incorrect. Please change it to 45.
#Q. How many NAs are there in Age column. Replace the NAs by the mean age.Following fn will give the mean age:
mean(titanic_train\$Age,na.rm = TRUE)
#Q. Add another column: Family_Members = 1(Self) + SibSp (gives number of siblings + spouse) + Parch (gives parents + children)

Best Regards
Samridhi

Alumni
Trainer

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Everybody,

Please find attached today's class notes (8th April - Descriptive Statistics / Data Visualization).

Regards
Samridhi

#### Attachments

• Class_Notes_8_Apr.pdf
344.5 KB · Views: 30

#### _27891

##### New Member
Alumni
Thank you Samridhi for the class notes.

#### _26870

##### Member
Alumni
Hi Everyone,

Here are some practice questions for all of you to work upon.

data("iris")
ir = iris

#Q. Find the average sepal length of Setosa species. Hint: use function "mean"

#Q. Find the different categories of species variable. Hint use "table" function on Species variable

#Q. Find which species has the highest Petal Width.

#Q. For all the virginica flowers having petal width = 2.0, make their petal length to 5.5

#--------------------------------------------------------------------------------------------------------------------------------------------------------
#titanic dataset

#Q. Find the number of passengers who survived
#Q. Find the age of Timothy
#Q. Find names of passengers having age>35
#Q. The age of Henry has been entered incorrect. Please change it to 45.
#Q. How many NAs are there in Age column. Replace the NAs by the mean age.Following fn will give the mean age:
mean(titanic_train\$Age,na.rm = TRUE)
#Q. Add another column: Family_Members = 1(Self) + SibSp (gives number of siblings + spouse) + Parch (gives parents + children)

Best Regards
Samridhi

#### _26870

##### Member
Alumni
#practice
data("iris")
ir = iris

#Q. Find the average sepal length of Setosa species. Hint: use function "mean"

#Q. Find the different categories of species variable. Hint use "table" function on Species variable

#Q. Find which species has the highest Petal Width.

#Q. For all the virginica flowers having petal width = 2.0, make their petal length to 5.5

questions

data("iris")
ir = iris
class(ir)

#Q. Find the average sepal length of Setosa species. Hint: use function "mean"
spices_avg = mean(ir\$Petal.Width)
spices_avg

#Q. Find the different categories of species variable. Hint use "table" function on Species variable
spices_names = table(ir\$Species)
spices_names

#Q. Find which species has the highest Petal Width.
max_petal_width = max(ir\$Petal.Width)
max_petal_width
ir\$Species[max_petal_width]

#Q. For all the virginica flowers having petal width = 2.0, make their petal length to 5.5
View(ir)
ir\$Petal.Length <- ifelse(((ir\$Species == "virginica")&(ir\$Petal.Width==2.0)),5.5,ir\$Petal.Length)
View(ir)

View(titanic_train)

#Find the number of passengers who survived
titanic_train\$Survived
sum(titanic_train\$Survived)
class(titanic_train\$Survived)

#Q. Find names of passengers having age>35
name_p <- titanic_train\$Name[titanic_train\$Age > 35]
name_p

#Q. How many NAs are there in Age column. Replace the NAs by the mean age.Following fn will give the mean age:
#solution
#calculating mean age
mean_age <- mean(titanic_train\$Age,na.rm = TRUE)
mean_age
#calulating total NAs in Age column
total_NA <- sum(is.na(titanic_train\$Age))
total_NA
#replacing NAs with mean age
titanic_train\$Age[is.na(titanic_train\$Age)] = mean_age
View(titanic_train)

#Q. Add another column: Family_Members = 1(Self) + SibSp (gives number of siblings + spouse) + Parch (gives parents + children)
Family_Members = 1 + titanic_train\$SibSp + titanic_train\$Parch
Family_Members
View(temp)
temp <- cbind(temp, Family_Members)
write.csv(temp, "modified_file.csv")
View(temp)

#### _26915

##### Richa Rao
Alumni
Hi Everyone.

Can someone guide me how and from where to download the lectures of weekend classes.

#### _26915

##### Richa Rao
Alumni
Assignment Solution:

data("iris")
ir = iris

#Q. Find the average sepal length of Setosa species. Hint: use function "mean"

mean(ir\$Sepal.Length[ir\$Species=="setosa"])

#Q. Find the different categories of species variable. Hint use "table" function on Species variable

table(ir\$Species)

#Q. Find which species has the highest Petal Width.

ir\$Species[max(ir\$Petal.Width)]

#Q. For all the virginica flowers having petal width = 2.0, make their petal length to 5.5

ir\$Petal.Width[which(ir\$Species== "virginica" & ir\$Petal.Width== 2.0)]= 5.5

#--------------------------------------------------------------------------------------------------------------------------------------------------------
#titanic dataset
#

#Q. Find the number of passengers who survived

sum(titanic_train\$Embarked=="S")

#Q. Find the age of Timothy

titanic_train\$Age[grep("Timothy", titanic_train\$Name)]

#Q. Find names of passengers having age>35

titanic_train\$Name[titanic_train\$Age>35]

#Q. The age of Henry has been entered incorrect. Please change it to 45.

titanic_train\$Age[grep("Henry", titanic_train\$Name)]=45

#Q. How many NAs are there in Age column. Replace the NAs by the mean age.Following fn will give the mean age:
mean(titanic_train\$Age,na.rm = TRUE)

sum(is.na(titanic_train\$Age))
titanic_train\$Age[is.na(titanic_train\$Age)]= mean(titanic_train\$Age,na.rm = TRUE)

#Q. Add another column: Family_Members =1(Self) + SibSp (gives number of siblings + spouse) + Parch (gives parents + children)

family_member=1+titanic_train\$SibSp+titanic_train\$Parch
titanic_train_new= cbind(titanic_train, family_member)

#### Kiran Kumar Varanasi

##### Member
Alumni
Dear Samridhi
The assignment is as follows

#Q. Find the average sepal length of Setosa species. Hint: use function "mean"

mean_ir_setosa <- mean(ir\$Sepal.Length[which(ir\$Species=="setosa")])

mean_ir_versicolor <- mean(ir\$Sepal.Length[which(ir\$Species=="versicolor")])

mean_ir_virginica <- mean(ir\$Sepal.Length[which(ir\$Species=="virginica")])

#Q. Find the different categories of species variable. Hint use "table" function on Species variable

cat_ir <- table(ir\$Species)

#Q. Find which species has the highest Petal Width.

ir\$Species[ir\$Sepal.Length %in% max(ir\$Sepal.Length)] -> Sp_Max_SepalLength
ir\$Species[ir\$Sepal.Width %in% max(ir\$Sepal.Width)] -> Sp_Max_SepalWidth
ir\$Species[ir\$Petal.Length %in% max(ir\$Petal.Length)] -> Sp_Max_PetalLength
ir\$Species[ir\$Petal.Width %in% max(ir\$Petal.Width)] -> Sp_Max_PetalWidth

#Q. For all the virginica flowers having petal width = 2.0, make their petal length to 5.5

i <- 1
for (i in 1:length(ir\$Species))
{ if (ir\$Petal.Width==2.0 && ir\$Species=='virginica')
{
ir\$Petal.Length <- 5.5
}
i <- i+1
}

#titanic dataset

#Q. Find the number of passengers who survived

table(titanic_train\$Survived)

0 1
549 342
Survived 342

#Q. Find the age of Timothy
titanic_train\$Age[grep(pattern = "Timothy", x = titanic_train\$Name, ignore.case = TRUE)]
 54 NA
Two people with surname Timothy

#Q. Find names of passengers having age>35

name_titanic <- function(k)
{ i <- 1
name_35 <- c()
for (i in 1:length(titanic_train\$Age))
{
if(is.na(titanic_train\$Age))
{j <- 0
}else if(titanic_train\$Age >= k)
{
name_35 <- c(name_35, titanic_train\$Name)}
i <- i+1
}
print(matrix(name_35, ncol=1))
}

#Q. The age of Henry has been entered incorrect. Please change it to 45.

titanic_train\$Age[grep(pattern = "Henry",x = titanic_train\$Name, ignore.case = TRUE)] <- 70

#Q. How many NAs are there in Age column. Replace the NAs by the mean age.Following fn will give the mean age:

mean(titanic_train\$Age,na.rm = TRUE)
summary(titanic_train\$Age)

Min. 1st Qu. Median Mean 3rd Qu. Max. NA's
0.42 21.00 29.00 31.27 40.00 74.00 170
> titanic_train\$Age[is.na(titanic_train\$Age)] <- mean(titanic_train\$Age, na.rm = TRUE)
> summary(titanic_train\$Age)

Min. 1st Qu. Median Mean 3rd Qu. Max.
0.42 22.00 31.27 31.27 36.00 74.00

#Q. Add another column: Family_Members = 1(Self) + SibSp (gives number of siblings + spouse) + Parch (gives parents + children)

titanic_train\$Family <- titanic_train\$SibSp + titanic_train\$Parch + 1
summary(titanic_train\$Family)

Min. 1st Qu. Median Mean 3rd Qu. Max.
1.000 1.000 1.000 1.905 2.000 11.000

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Everyone.

Can someone guide me how and from where to download the lectures of weekend classes.

Hi Richa,

Best Regards,
Samridhi

#### _26915

##### Richa Rao
Alumni
Hi Samridhi,

While discussing Boxplot , you mentioned that there is one more usage of Boxplot apart from univariate visualization of numeric/continuous variable. Could you explain what other usage you were referring to.

#### Manish Kumar_28

##### Member
Alumni
data("iris")
ir<-iris
View(ir)
#avg sepal length
print(mean(ir\$Sepal.Length))
mean(ir\$Sepal.Length[ir\$Species=="setosa"])

#different categories of species varible
table(ir\$Species)
# doubt: what if i want to see only the categories not the count? we could have used unique also.

#Q. Find which species has the highest Petal Width.
vMaxPetalLength<- max(ir\$Petal.Width)
ir\$Species[ir\$Petal.Width==vMaxPetalLength]
#doubt: Why it gives me Levels?

#Q. For all the virginica flowers having petal width = 2.0,
# make their petal length to 5.5
ir[ir\$Species=="virginica" & ir\$Petal.Width==2.0,]\$Petal.Length <-5.5
ir[ir\$Species=="virginica" & ir\$Petal.Width==2.0,]

############################### Titanic #######################################
View(titanic_train)
#Q. Find the number of passengers who survived
sum(titanic_train\$Survived)

#Q. Find the age of Timothy
df<-titanic_train[grep("timothy",titanic_train\$Name,ignore.case = T),]
TimothyAge<-data.frame(df\$Name,df\$Age)
colnames(TimothyAge)=c("Name","Age")
View(TimothyAge)
#Q. Find names of passengers having age>35
df<-titanic_train[which(titanic_train\$Age>35),]
View(df)
PassengerGT35<-data.frame(df\$Name,df\$Age)
View(PassengerGT35)
#Q. The age of Henry has been entered incorrect. Please change it to 45.
titanic_train[grep("Henry",titanic_train\$Name,ignore.case = TRUE),"Age"]<-45
View(titanic_train)
#Q. How many NAs are there in Age column. Replace the NAs by the mean age.Following fn will give the mean age:
mean(titanic_train\$Age,na.rm = TRUE)
summary(titanic_train\$Age)
titanic_train[is.na(titanic_train\$Age),]\$Age<-mean(titanic_train\$Age,na.rm = TRUE)
#Q. Add another column: Family_Members = 1(Self) + SibSp (gives number of siblings + spouse) + Parch (gives parents + children)
titanic_train\$FamilyMembers<-titanic_train\$SibSp+ titanic_train\$Parch+1
titanic_train\$'titanic_train\$SibSp + titanic_train\$Parch + 1'<-NULL

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Samridhi,

While discussing Boxplot , you mentioned that there is one more usage of Boxplot apart from univariate visualization of numeric/continuous variable. Could you explain what other usage you were referring to.

Hi Richa,

Let's discuss this in the class

Regards,
Samridhi

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Everyone,

Please find attached the class notes of today's session (in R)

Best Regards,
Samridhi

#### Attachments

• Class_Notes_14Apr_ApplyFamily.pdf
178.6 KB · Views: 25

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Everyone,

Today's assignment question: Please find the z* values for significance level of 5%, 1% and .1% for right tail test, left tail test and for 2-tail test.

Regards
Samridhi

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Everyone,

Please find attached the class notes discussed today.

Best Regards
Samridhi

#### Attachments

• Class_notes_15Apr_dplyr.pdf
192.3 KB · Views: 23
• Class_notes_15Apr_InferentialStatistics.pdf
341.1 KB · Views: 24

Alumni
Trainer
Hi Everyone,

Best Regards,
Samridhi

#### Attachments

• DataManipulation_Apply_Dplyr.pdf
320.7 KB · Views: 20

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Everyone,

Please find attached the assignment on Hypothesis Testing I and II. Please attempt the questions and submit in the community forum.

Best Regards
Samridhi

#### Attachments

• Assignment Statistics.pdf
800.8 KB · Views: 27
• Lesson 7 Basic Stats.pdf
328.3 KB · Views: 21

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Everyone,

Also, I forgot to mention the other assignment question with respect to correlations - think of the cases where:

- correlation exists but the causation relationship does not exist
- causation exists but correlation is not there

Best Regards
Samridhi

#### _26915

##### Richa Rao
Alumni
Hi Samridhi/All,

If we are conducting two tail test with alpha value 5 %, where each side will be alpha/2 ie. 2.5%. Now, while calculating critical value at this alpha like= norminv(0.05,mean,std_dev), suppose the value came out to be 6.4. So, do we divide this critical value by 2 for each side(3.2 each side for alpha/2) or will it be taken as it is ie 6.4 as critical value each side.

#### _27759

##### Prasenjit Das
Alumni
Priyanka,

I attended Data Science with R Apr 14 class, but it is showing as not attended in my classes section. Please check.

#### Samridhi Dutta

##### Well-Known Member
Alumni
Trainer
Hi Samridhi/All,

If we are conducting two tail test with alpha value 5 %, where each side will be alpha/2 ie. 2.5%. Now, while calculating critical value at this alpha like= norminv(0.05,mean,std_dev), suppose the value came out to be 6.4. So, do we divide this critical value by 2 for each side(3.2 each side for alpha/2) or will it be taken as it is ie 6.4 as critical value each side.

Hi Richa,

We discussed in the class - norminv / normdist / normsdist / normsinv formulae work only on left tail probability. So if I want the value at 5% significance level, we can get through norminv(.975, mean, stddev) and norminv(.025, mean, stddev).

For t-dsitribution, we have to input the extreme probabilities (either left tail 5%; or rt tail 5%; or 2-tail 5%, 2-tail 5% means 2.5% on left tail and 2.5% on right tail).

Let me know if this needs further explanation.

Regards,
Samridhi

#### _26915

##### Richa Rao
Alumni
Hi Everyone,

Today's assignment question: Please find the z* values for significance level of 5%, 1% and .1% for right tail test, left tail test and for 2-tail test.

Regards
Samridhi

At 5% significance level:

For Left tail test:

-1.64485363

For right tail test:

1.644853627

For 2 tail test:

-1.95996398 & 1.959963985

At 1% significance level:

Left tail test:
-2.32634787

Right tail test:
2.326347874

2 Tail test:
-2.5758293 & 2.575829304

At 0.1% significance level:

Left tail test:
-3.09023231

Right tail test:
3.090232306

2 Tail test:
-3.29052673 & 3.290526731

• Samridhi Dutta
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