Dataset:  color_onlineshopping.csv

Source: Y.-C. Hsieh, H.C. Chiu, Y.C. Tang, M. Lee (2018). "Do Colors
Change Realities in Online Shopping," Journal of Interactive Marketing,
Vol. 41, pp. 14-27.

Description: Results of perceived quality by subjects in a 3-Factor 
experiment of online shopping. Factors are web page hue (1=Blue, 2=Red),
Brightness (1=Dark, 2=Bright), and Price (1=Low, 2=high). Unbalanced
sample sizes. Data simulated to match trt means/SDs.

Variable names:
quality
trt_id
hue
bright
price
X_hue   /* Effect coding: Blue=1, Red=-1 */
X_bright /*  "     "      Dark=1, Bright=-1 */
X_price  /*  "     "      Low=1, High=-1 */