STEP 1: DESIGN THE EXPERIMENT

We will utilize statistical data to investigate if consumers who are primed have a higher interest in a product than those who are unprimed.

STEP 2: COLLECT (OR LOAD) DATA

preference<- read.csv("preference.csv")
preference
##    preference primed
## 1         1.8      0
## 2         0.1      0
## 3         4.0      0
## 4         2.1      0
## 5         2.4      0
## 6         3.4      0
## 7         1.7      0
## 8         2.2      0
## 9         1.9      0
## 10        1.9      0
## 11        0.1      0
## 12        3.3      0
## 13        2.1      0
## 14        2.0      0
## 15        1.4      0
## 16        1.6      0
## 17        2.3      0
## 18        1.8      0
## 19        3.2      0
## 20        0.8      0
## 21        1.7      1
## 22        1.7      1
## 23        4.2      1
## 24        3.0      1
## 25        2.9      1
## 26        3.0      1
## 27        4.0      1
## 28        4.1      1
## 29        2.9      1
## 30        2.9      1
## 31        1.2      1
## 32        4.0      1
## 33        3.0      1
## 34        3.9      1
## 35        3.1      1
## 36        2.5      1
## 37        3.2      1
## 38        4.1      1
## 39        3.9      1
## 40        1.1      1
## 41        1.9      1
## 42        3.1      1
library(ggplot2)

STEP 3: DESCRIBE DATA

A research team randomly assigned participants to either a primed condition (denoted 1 in the data set) or non-primed condition (denoted 0). Each participant was asked to indicate their attitude toward a product on a continuous rating scale ranging from 0 (dislike very much) to 6 (like very much). A bottle of pet shampoo with a picture of a collie on the label was the product. Prior to giving their score, however, participants were asked to do a word find where four of the words were common across groups (pet, grooming, bottle, label) and four were either related to the image (dog, collie, puppy, woof for the primed group) or image conflicting (cat, feline, kitten, meow for the non-primed group). Responses on 44 individuals (20 in the non-primed group and 22 in the primed group) were recorded to one decimal place.

STEP 4: IDENTIFY THE PUROSE OF THE STUDY

The purpose of this study is to indicate if consumers who are primed have a higher interest in the product than those who are not primed.

STEP 5: VISUALIZE DATA

library(ggplot2)
ggplot(data=preference, mapping=aes(x=as.factor(primed), y=preference)) + geom_point()

STEP 6: INTERPRET THE PLOT

The people that were primed have a higher preference for the product than the people that were not primed.

STEP 7: FORMULATE THE NULL HYPOTHESIS

There is no difference in preference of the product between the subjects that were primed, and the subjects that were not primed. In other words, consumers who are primed and unprimed will have the same mean.

STEP 8: IDENTIFY THE ALTERNATIVE HYPOTHESIS

People that are primed have more of a preference for the product than people that were not primed. In other words, consumers who are primed will have a higher mean than the customers that were not primed.

STEP 9: DECIDE ON TYPE OF TEST

I am going to run a t-test on this data, which means I will be testing my hypotheses (null and alternative) about population means of a quantitative variable.

STEP 10: CHOOSE ONE SAMPLE OR TWO

Two sample.

STEP 11: CHECK ASSUMPTIONS OF THE TEST

library(ggplot2)
ggplot(data=preference) + geom_qq(mapping=aes(sample=preference, color=as.factor(primed)))

STEP 12: DECIDE ON A LEVEL OF SIGNIFICANCE OF THE TEST

I will use the traditional level of significance, 0.05.

STEP 13: PERFORM THE TEST

t.test(formula=preference~as.factor(primed), data=preference)
## 
##  Welch Two Sample t-test
## 
## data:  preference by as.factor(primed)
## t = -3.2072, df = 39.282, p-value = 0.002666
## alternative hypothesis: true difference in means is not equal to 0
## 95 percent confidence interval:
##  -1.577912 -0.357543
## sample estimates:
## mean in group 0 mean in group 1 
##        2.005000        2.972727

STEP 14: INTERPRET THE P-VALUE

The p value is much less than 0.05, which rejects the null hypothesis.

STEP 15: INTERPRET THE CONFIDENCE INTERVAL

0 is not present in the range of confidence, so therefore we reject the null hypothesis.

STEP 16: INTERPRET THE SAMPLE ESTIMATES

There is a statistically significant different between the primed and not primed group, which means that the primed group showed higher preference to the product than the not primed group.

STEP 17: STATE YOUR CONCLUSION

To conclude, the primed group had a higher preference for the product than the not primed group.