VW PMS.Rmd

---
title: "Price Sensitivity"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)

library(pricesensitivitymeter) 
library(readxl) # To read excell files
library(ggplot2) # To create plots
```

```{r pressure, echo=FALSE}
my_data <- data.frame(read.csv("my_data.csv"))
```

```{r BLEND, echo=FALSE}
# Select the respective columns
output <- psm_analysis(toocheap = my_data[,2], 
                       cheap =  my_data[,3], 
                       expensive =  my_data[,4],
                       tooexpensive =  my_data[,5],
                       interpolate =TRUE
                       )

summary(output)
```

```{r plot}
psm_plot <-  function(output.psm, plot_title) {
  psmplot <- ggplot(data = output.psm$data_vanwestendorp, aes(x = price)) +
  annotate(geom = "rect", # shaded background area for range of acceptable prices
           xmin = output.psm$pricerange_lower,
           xmax = output.psm$pricerange_upper,
           ymin = 0, ymax = Inf,
           fill="grey50", alpha = 0.3) +
  geom_line(aes(y = ecdf_toocheap, # line: too cheap
                colour = "too cheap",
                linetype = "too cheap"),
            size= 1) +
  geom_line(aes(y = ecdf_tooexpensive, # line: too expensive
                colour = "too expensive",
                linetype = "too expensive"),
            size = 1) + 
  geom_line(aes(y = ecdf_not_cheap, # line: not cheap
                colour = "not cheap",
                linetype = "not cheap"),
            size = 1) +
  geom_line(aes(y = ecdf_not_expensive, # line: not expensive
                colour = "not expensive",
                linetype = "not expensive"),
            size = 1) + 
  annotate(geom = "point", # Indifference Price Point (intersection of "cheap" and "expensive")
           x = output.psm$idp, 
           y = output.psm$data_vanwestendorp$ecdf_not_cheap[output.psm$data_vanwestendorp$price == output.psm$idp],
           size = 3.5,
           colour = "#6a6a6a") + 
  annotate(geom = "point", # Optimal Price Point (intersection of "too cheap" and "too expensive")
           x = output.psm$opp, 
           y = output.psm$data_vanwestendorp$ecdf_toocheap[output.psm$data_vanwestendorp$price == output.psm$opp],
           size = 3.5,
           colour = "#6a6a6a") + 
  annotate(geom = "point", # Point of Marginal Expensiveness (intersection of "not expensive" and "too expensive")
           x = output.psm$pricerange_upper, 
           y = output.psm$data_vanwestendorp$ecdf_not_expensive[output.psm$data_vanwestendorp$price == output.psm$pricerange_upper],
           size = 3.5,
           colour = "#6a6a6a") +
  annotate(geom = "point", # Point of Marginal Cheapness (intersection of "not cheap" and "too cheap")
           x = output.psm$pricerange_lower, 
           y = output.psm$data_vanwestendorp$ecdf_not_cheap[output.psm$data_vanwestendorp$price == output.psm$pricerange_lower],
           size = 3.5,
           colour = "#6a6a6a") 


# Labels and Colours
psmplot +
  labs(x = "Price",
       y = "Share of Respondents (0-1)",
       title = sprintf("%s\nPrice Sensitivity Meter - Van Westendorp Method", plot_title),
       caption = "Shaded area: Range of acceptable prices\nOPP: Optimal Price Point\nIDP: Indifference Price Point\nPME: Point of Marginal Expensiveness\nPMC: Point of Marginal Cheapness")  + 
  scale_colour_manual(name = "Legend",
                      values = c("too cheap" = "#009E73",
                                 "not cheap" = "#009E73",
                                 "not expensive" = "#D55E00",
                                 "too expensive" = "#D55E00")) + 
  scale_linetype_manual(name="Legend",
                        values = c("too cheap" = "dotted",
                                   "not cheap" = "solid",
                                   "not expensive" = "solid",
                                   "too expensive" = "dotted")) + 
  annotate(geom = "text", # Label of Indifference Price Point
           x = output.psm$idp, 
           y = output.psm$data_vanwestendorp$ecdf_not_cheap[output.psm$data_vanwestendorp$price == output.psm$idp] + 0.07,
           label = paste("IDP ", output.psm$idp)) + 
  annotate(geom = "text", # Label of Optimal Price Point
           x = output.psm$opp,
           y = output.psm$data_vanwestendorp$ecdf_toocheap[output.psm$data_vanwestendorp$price == output.psm$opp] - 0.05,
           label = paste("OPP ", output.psm$opp)) +
  annotate(geom = "text", # Label of Point of Marginal Expensiveness
           x = output.psm$pricerange_upper + 12, 
           y = output.psm$data_vanwestendorp$ecdf_not_expensive[output.psm$data_vanwestendorp$price == output.psm$pricerange_upper],
           label = paste("PME ", output.psm$pricerange_upper)) +
  annotate(geom = "text", # Label of Point of Marginal Cheapness
           x = output.psm$pricerange_lower - 11, 
           y = output.psm$data_vanwestendorp$ecdf_not_cheap[output.psm$data_vanwestendorp$price == output.psm$pricerange_lower],
           label = paste("PMC ", output.psm$pricerange_lower)) +
  theme_minimal()
}
```

```{r BLEND, echo=FALSE}
psm_plot(output, "MY PLOT")
```