[danielmarkbruce]

This isn't right. It could in fact mean prices are going down.

Had we just reported a month on month -0.4% instead of 0.4%, the yoy rate would have been reported as 6.9%. A headline of 6.9% would mean prices are actually going down.

[meragrin_]

Anything positive YoY means prices have gone up overall over the last year. For prices to have gone down in general over the last year, the YoY would have to be negative. A headline of 6.9% would mean prices have gone up.

[colinmhayes]

You're just talking about different time frames. Yearly inflation can be positive and prices can also be lower than they were last month. Ergo prices are going down but inflation still positive.

[danielmarkbruce]

The slope of price v time would be going down if they'd posted 6.9% yoy.

The discussion is around how the numbers should be interpreted. There isn't confusion around what they have literally reported.

[dcow]

Nope. You are continually overlaying data with different X axis and trying to draw conclusions and sound authoritative and it’s just sloppy and irresponsible.

The instantaneous slope would be negative if the last month happened to observe a slight decrease, true. But the slope of the line between last year and this year would be positive.

Both statements can be true:

1. prices just fell slightly since last month

2. prices have risen overall since last year

EDIT: you edited your comment I’m not going to update mine.

[danielmarkbruce]

Same x axis - time. CPI is a time series, you get a point every month. Everyone is trying to draw conclusions, it's the point of this thread.

>> The instantaneous slope would be negative if the last month happened to observe a slight decrease, true

This is sloppy. It's fine, it's a forum, we aren't writing academic papers.

Nobody is trying to figure the slope of the straight line between the two points, that's what is already reported.

Yes, both can be true.

[dcow]

Sigh. Obviously we’re talking time here. The scale on the X axis, the interval that appears on the graph between two points, is different if every unit is a month vs a year. Months and years are different units of time.

IDK… nobody is really trying to figure out how to interpret the data. People were just commenting that “declines to X%” actually still means that it’s gone up YoY and not that it’s declining YoY and here you are yelling that actually it is declining because recently it went down. Which is false, YoY.

[danielmarkbruce]

Scale is the same. The CPI reports every month. It's one chart, a single index, one point per month.

They just take the recent point and the point from a year ago and do the math and report the change. For mom they do the recent point and the one before that, do the math and report.

Some people actually know what the CPI is, how it gets reported, and understand the shortcomings of said reporting. If you aren't one of those people, it's silly to go around correcting others.