This code Q2 % filter(Year %in% c(2020, 2021)) %>% group_by(region) %>% summarise( Mean = round(mean(AveragePriceConv), 2), Median = round(median(AveragePriceConv), 2), Third_Q = round(quantile(AveragePriceConv, 0.75), 2),

This code

Q2 <- fifth_step %>% filter(Year %in% c(2020, 2021)) %>% group_by(region) %>% summarise( Mean = round(mean(AveragePriceConv), 2), Median = round(median(AveragePriceConv), 2), Third_Q = round(quantile(AveragePriceConv, 0.75), 2), StDev = round(sd(AveragePriceConv), 2), CV = round(StDev/ mean(AveragePriceConv), 2) %>% select(region, Mean, Median, Third_Q, StDev, CV)) %>% arrange(desc(CV)) %>% as.data.frame() %>% slice_head(n = 10)

gives this error

Error in summarise(., Mean = round(mean(AveragePriceConv), 2), Median = round(median(AveragePriceConv), : In group 1: `region = "Albany"`. Caused by error in `UseMethod()`: ! no applicable method for 'select' applied to an object of class "c('double', 'numeric')"