Which factor can lead to a shift in the demand curve in economic analysis?

A shift in the demand curve occurs when there is a change in any factor other than the price of the good itself. When consumer income changes, it influences buyers' purchasing power and thus their ability to buy goods. If consumer income increases, people generally have more money to spend, which can lead to an increase in the quantity demanded at every price level. This effectively moves the demand curve to the right. Conversely, if consumer income decreases, the quantity demanded at various price levels would also decrease, causing the demand curve to shift to the left.

The other factors mentioned do not lead to shifts in the demand curve: changes in the price of the good itself result in movements along the demand curve rather than shifts. Improvements in technology typically affect supply rather than demand, as they impact how goods are produced. Similarly, changes in production costs relate to the supply side of the market; they influence the supply curve rather than the demand curve. Thus, only changes in consumer income truly cause a shift in the demand curve.