Task1DAssingment

UPI: msuv992

library(s20x)
nzfood.df = read.csv("NZ_Food_Prices.csv", header=TRUE)
avocado.df = nzfood.df[nzfood.df$Item == "Avocados",]
avocado.df = avocado.df[!is.na(avocado.df$Value),]

boxplot(avocado.df$Value)

Center : 8.63 Spread : between 3.38 - 28.67 Skew : Right-skewed

normcheck(avocado.df$Value)

summaryStats(avocado.df$Value)

Minimum value:           3.38 
Maximum value:           28.67 
Mean value:              9.7 
Median:                  8.63 
Upper quartile:          11.22 
Lower quartile:          7.19 
Variance:                17.54 
Standard deviation:      4.19 
Midspread (IQR):         4.03 
Skewness:                1.77 
Number of data values:   211 

t.test(avocado.df$Value, mu=10)

    One Sample t-test

data:  avocado.df$Value
t = -1.0354, df = 210, p-value = 0.3017
alternative hypothesis: true mean is not equal to 10
95 percent confidence interval:
  9.133091 10.269847
sample estimates:
mean of x 
 9.701469 

Methods and Assumptions We want to identify whether the true mean price of avocados is equal to $520 as according to a popular YouTube guru. We accomplish this by carrying out a on sample t-test.

The avocados are assumed to be purchased independently of each other per week. The boxplot and QQ plot show that the data is right-skewed however Central Limit Thereom can be applied to justify our assumption of Normality.

The model fitted is \(Value_i\) = \(\mu + \varepsilon_i\) where \(\mu\) is the mean value of avocados and \(\varepsilon_i \overset{\text{iid}}{\sim} N(0, \sigma^2)\).

Executive Summary Our aim in analysing this data set is to confirm whether the YouTube guru’s claim about the weekly cost of $10 for a kg of avocado is true.

The results of our test shows that our mean price for avocados historically is between 9.10 and 10.30 NZ dollars.