Most people believe that the price of altcoins' is determined by the price of bitcoin and that they tend to follow it's market movements.
I partially disagree with this. I have studied prices of coins and tokens on CMC and the fluctuations of each currency seems to be unique and independent of any other digital currency. Some show strong pumps when BTC goes down and some heavy dumps when BTC is rising.
Undoubtedly, there are market forces and factors which affects most currencies, this is not influenced by bitcoins price, it rather controls bitcoins' price as well as others.
So when trading or investing, make sure you treat each currency differently as they have different utilities.
Maybe in some instance, the prices of altcoins may be dependent on either Ethereum or Bitcoin because it was intended to be set into a value equal to those. So when the price sinks or rises, the price value also do. In some instance on the other hand, the uniqueness of the price came as a reaction of the buyers and sellers of the set value based on the movement of Bitcoin or Ethereum to purchase a distint token in the market so both perception are correct depending upon how you interpret it manually. It is just a technicality on comparing different cryptocurrencies.