Main effects & interactions

[@menuguide]

Funny that the example was sleep deprivation, because I fell asleep during the lectures on main effects and interactions and missed learning this. Thank you so much for helping me out!

[@JimGrange.]

Hahaha, perfect :)

[@DeathBoyZ5012]

lmao same i just didnt show up to lecture

[@rachaelberglund7221]

The easiest to understand explanation of all the different videos i have looked at. Perfect! Thank you!

[@larissacury7714]

THANK YOU THANK YOU THANK YOUUUUUUUUUUU!!! Sorry for the caps, but I've never seen SUCH A CLEAR explanation of this. THANK YOU!

[@AldosWorldTV]

amazing explanation, thanks boss

[@ManonAndredeStAmant]

This is a super helpful explanation to a relatively complex topic, it makes it seem very intuitive and I wanted to thank the author of this video

[@JimGrange.]

Glad it helped! Thanks for watching.

[@souvikroychoudhury3612]

After reading text books , reading so many articles and research paper and seeing many youtube videos I thought of giving up the topic but at last I found your video and it made the concept all clear. Thanks a lot from India for uploading such nice video on this complex topic.

[@nnhouston]

Oh my goodness! I finally get it! Thank you so much for making this topic so understandable.

[@garyogden4806]

Excellent video. Searching on KZbin for the last hour or so for a clear explanation on the meaning of main effects and interaction and this video was the best by far.

[@sarocturtlegaming7306]

the vid my professor attached to teach us this cuz it's an online class is 2 hours long. You just summed up 2 hours, held my attention, and made it make sense. omg THANK YOU!!!!!! - a sleep deprived nursing student who's trying to self teach herself stats

[@MiriamIllions]

Thanks! You really helped me understand this better.

[@JimGrange.]

I hope you all find this video useful! If you have any questions, please do drop me an email. And if the video has REALLY helped and you want to buy me a beer, please see www.paypal.com/donate/?hosted_button_id=L692FVF8PNUKU

[@AlexBollich]

really good!Thank you very much!

[@Mimi-pq5zf]

THANK YOU SO SO SO MUCH! This was so helpful and clear. I have struggled with this my entire undergraduate year.

[@anadepina7051]

Great explanation! Thank you.

[@christophedelhaye4754]

Hi Jim, I didn't sleep well, I'm gonna take a big dose of caffeine, thanks for the advice :) and thank you a lot for the explanations.

[@petersailing1]

Was going to send a few bob, but PayPal fee would have got as much as you! So sorry but thanks anyway

[@swiftedg]

Hi Jim, thank you for your simplified version of understanding fANOVA! Choosing the right statistical test gets quite difficult with many groups, and multi-dimensional output variables, this helped a lot!

[@lennardjer9354]

Thank you Jim for this simple explanation about the two topics. At min. 6:30 (about interaction) I suggest to note the difference on 1h and 24h of caffeine on the percent correct/ y-line.. The difference of 10 (percent) is on the y-line/vertical line. Regards and keep this up!

[@farookjahoor4977]

For a now retired but still active biomedical scientist this is the best explanation I've ever seen of main effects and interaction

[@JimGrange.]

High praise indeed! Thank you so much :)

[@nicoleyatawara5825]

holy cow, you made that so easy to understand! i can't believe none of my teachers could explain it so simply! thank you so much! research methods has been the bane of my existence because i just can't seem to process it!

[@nicoleyatawara5825]

and i'm doing my masters in clinical and health psych at UWL btw, and i almost dropped out because of the research methods aspect of it! i'm an otherwise A student and graduated magna cum laude with my BSc! so really, i can't thank you enough!

[@gedoffmydupata]

I go to school in the U.S. and was so confused learning about this, but this video helped me understand factorial designs better, thank you!

[@nataliedorantes4380]

This is the video that helped my brain wrap around the topic main effect and interaction. Thank very much !

[@ziyuyu3974]

My lecturer would not stop going on tangents and then pausing only to attempt three more times to explain what these effects are. My test is tomorrow, you are a life saver. Thank you!

[@JimGrange.]

How did the test go?

[@timmydecraen7258]

This sleep deprived Tilburg University student thanks you very much! Great explanation and very useful for my research note.

[@stormsaddler4910]

Oh my GOODNESS thank you so much for this. My discussion went over it so quickly I didn't catch any of it! Thank you a thousand times over

[@ilovecardgames5839]

After a day of trying to figure this out in my textbook, I finally looked it up on KZbin. You just resolved a days worth of stress. Fuck the textbook. I’m using KZbin from now on.

[@lawsen3719]

Been stuck on this in 2 days, this video cleared everything up. Thank you Jim!

[@JimGrange.]

Absolute pleasure!

[@modasbycaroline]

I'm currently in a research methods class and this video has really helped me figure out main effects. My teacher gave us an exam including main effects and didn't explain at all like you did. Thank you.

[@ofirshorshy8281]

Thank you this is so much more clear than the mess my lecturer left me with!!

[@emmafowler182]

Most useful exploration of this I have read or seen - thank you

[@joediebrandwood4711]

Thank you for this video!!! I was tied up in knots over my main effects and interactions as there was significant main effects but not interactions. Made perfect sense. Funny how you can spend 3years at uni being lost in statistics, yet a simple video works wonders :-D Thank you!

[@timirvin1777]

Most helpful. The best explanation I've seen on this. Thank you.

[@kyledunlap4042]

Very helpful video. Thank you for taking the time to post it and make it public.

[@JimGrange.]

My pleasure! Thanks for your feedback

[@texaspolygraph]

Thank you so much Jim. That really made it clear. You have a superb way of explaining things.

[@arsenalboii1753]

AMAZING VIDEO. you're saving lives, my friend!

[@lovingmode]

Awesome job Jim! I only spent one whole week trying to understand anything at all about main and interaction effect, banging my head and hoping I could drill it in (thanks to a no-so-good UC Berkeley PhD psych teacher), and then you happened in my life!! (and this is a junior college psych class!!). Thank you!!!

[@JimGrange.]

I'm really pleased it helped :)

[@tatjanaf.5284]

I am having my very last exam of my whole study in 2 hours and this topic was something I just could not wrap my head around. Now it finally make sense to me. (And it is so ironically that I am sleep deprived and only working on caffeine fuel). Thank you!

[@gentle2005phir]

You have hit the bull's eye. Crystal clear explanation. Salute

[@jessicahai93]

This is so great! Thank you for providing this to your students and the rest of the students in need of an explanation.

[@rebrose527]

This was a great explanation, especially describing how to interpret the line graph! Thanks!!

[@hengyewken96]

Thank you very much for your explanation!!! This video really helps me understand better about main effects and interactions!!!

[@limabean2327]

This helped so much to see it in a real example. My lecturer showed them as A and B so I had no idea what was happening

[@JimGrange.]

Glad it helped!

[@fatimahbahrami3714]

That was the best video about this topic. Thanks a lot!

[@michellebrelaz4478]

Thank you! This made absolutely no sense before, and I just got a perfect score on a test after I listened to this! :)

[@eyveneen]

I put this video in my pocket! Awesome and clearly to the point thank you!

[@gillnijs467]

WISH YOU WERE MY LECTURER

[@JimGrange.]

Thanks!

[@flashcre8or]

I'm not in your class but this is going to help me pass mine! Thanks Jim!

[@JimGrange.]

Thanks for the kind words!

[@traceywilkie504]

thank you - just completing the last assignment of my Research Methods in Education / online and this helped a lot Jim ! Cheers fro NZ :D

[@yael123gut]

Thank you! Such a great and clear explanation!

[@chitluk4679]

having exam about these atm and its so great that i found this video, thank you so much mate :)

[@JimGrange.]

Good luck in your exams!

[@anncung9821]

Very simple to understand the complex concept, thank you very much

[@ap3he]

Thank you so much! You just saved me for finals :')! Please keep uploading, you explain things perfectly :D

[@JimGrange.]

Wow, that's great to hear :)

[@almond0w059]

Thank you sooooo much for this video!! My GPA has been saved.

[@angelosands9606]

Thanks for making it short, sweet, and to the point! I wish my minister would do the same in church!

[@SandyG1966]

This is great, it really helped me understand main effect and interaction. Thank you!

[@cupcaketv5673]

Thank you so much for this! Just one thing regarding the interaction effect. When I saw a few graphs showing two variables that cross each other while both variables had the same level of gradient, I at first thought there was no interaction effect. Since yes, one variable rises while the other one falls, but both had the same level of gradient. But there is still an interaction effect, as I found out. So I personally find it easier to memorize that there's always an interaction effect as long as the two variables aren't parallel.

[@JimGrange.]

That's a great way of thinking about it!

[@cupcaketv5673]

@@JimGrange. Thank you :) it's good to have this method confirmed by an expert haha

[@missnickix]

thank u Jim. A student from Greenwich university, this was VERY helpful!

[@JimGrange.]

My pleasure!

[@missnickix]

i got a 2:1 in my exam thank u :)

[@JimGrange.]

Superb! Congratulations! :)

[@liulim3478]

Clear explanation. This helps me a lot! Thank you~~

[@MaryAnneAchieng]

this makes so much more sense now, thanks!

[@pearlsop]

Thank you so much!!!! .You save my final examination's score!!!

[@coolkidkidcool1212]

literally same

[@Dragon_loot]

I have an exam tomorrow for my research methods class, thank you for this video!

[@infinite101_]

I'm not even from this uni and I wish you were one of my lectures 😔

[@RIAJMAHMUD-g5b]

best explanation on this topic .Thank you.

[@gradstudent8942]

Thank you!!! This was so helpful. Please keep posting videos!

[@JimGrange.]

I will! Email any requests to [e-mail]!

[@DJKorosiv]

this was beautifully described and the example was easy to interpret! thanks!!

[@aidav9]

Amazing video! Very well explained, thank you. Do you have another video where you explain how to test whether these effects are significant or not? Would be greatly appreciated!

[@barendrb]

I learned how to look up F scores in the table, and that the root of an F-score equals a T-score. But what happens with the Degrees of freedom? how do you know which one to use to use the T-table?

[@allysonharlan-vidil4229]

Thank you so much!!! I was really struggling with this concept and not being able to wrap my head around it.

[@JimGrange.]

I'm glad it helped!

[@drumashreedk27]

can I have clarity about further analysis after getting interaction effect significant in 2*2 factorial design...

[@joonyoon7900]

the next step would be the POSTHOC analysis. if the interaction term is significant, the two groups should be analyzed separately with one-way ANOVA (y=a for b=1, y=a for b=2). if not, consider a model without the interaction term, but that has two covariates ( y= a+b+error).

[@kanikagupta7684]

In order to be really sure whether or not there were significant differences in the data what should be included in the graphs that is missing?

[@emilyconley4967]

Very clear explanation--thanks, sir.

[@katefox2240]

what was the value of the interaction? I understand that the change in the caffeine pill sample was small, 10, and the change in the placebo was great, 75, so does this make the interaction effect 65? thanks :)

[@rfm1313]

This was phenomenal. - Neuroscience Master's Student

[@JimGrange.]

You are too kind; thank you!

[@jacobomollo5283]

excellent. well simplified. i have clearly understood

[@love14514]

Does the same explanation apply to a moderated regression analysis ? Let's say we get all coefficients as significant / moderator is dummy coded 1 for women and 0 for men. If we have a significant negative coefficient for the interaction term, we could say there is a decrease in Y as X increases, but this decrease is stronger for the women's group? How can we better explain the interaction effect when reporting results in a journal? The effect of X on Y is stronger in women? Do we report the difference in numbers? Could you provide an example of how to formally report a moderated regression with a dummy variable?

[@JimGrange.]

Yes, a moderated regression is the same as an interaction. ANOVA is basically regression in disguise.

[@szhan1023]

So clear to understand, thanks you so much!!!

[@joeperazzo6180]

AMAZING! Thank you so much for this!

[@toxicXXbutterfly]

This video helped clear things up. Thank you so much!

[@joviepacana6099]

What certain test to perform if the interaction is significant?

[@taladiv3415]

Thank you sir for making sense of this topic :)

[@richellek3614]

this was soo clear :)

[@sjsphotog]

Thank you. I hink you only forgot to mention that if they will eventually INTERSECT on one end of the lines ( which in this case yes they will intersect on the upper left) meaning if we used a different amount of caffeine in the pill or had them skeep deprived less than 1 hour. No intersection = no interaction.

[@bozenamiocic9843]

Really good explaining!

[@tunkabeantans]

Thank you!!! This was very well explained & helped quite a lot

[@JimGrange.]

I'm seriously glad it helped!

[@shanellem7091]

This is great and it helped me a lot! Thank you!

[@naimasaid2451]

Thank you! This might have saved me

[@opeyemialabi4572]

Great explanation. Thank you.

[@femaleforester]

Do I understand correctly that the effects of the single variables are negative (negative slope) whilst the interaction effect is positive (alleviates the negative effect of sleep deprivation)?

[@kamilas7737]

Excellent video 🌟❤️

[@JimGrange.]

Ahhhh thanks so much, @kamilas7737! Is there anything else you'd like to see explained in a tutorial video?

[@redblock7081]

Thank you from the University of Cape Town!

[@doomkoff9932]

This was super useful! Thanks a bunch!

[@kathyweeds]

Just to further understand how the main effect and interaction relate- while it is the interaction that we focus on in statistical analysis, would one say that the presence of an interaction qualifies the main effect, or is that irrelevant?

[@laurencebacchus5066]

I think the main effect (sleep deprivation) is qualified by the interaction (type of pill).

[@passion830217]

Thanks for this video. It is easy to understand.

[@FrozenGravy]

If the main effects are significant but the interaction effect is not, is it acceptable to continue with a posthoc test for multiple comparisons, or is the posthoc test reserved for when an interaction effect exists?

[@Merluza999]

best video on the subject

[@meialua73]

Thank you very much Jim. It help me a great deal.

[@naznigde2192]

thank you SOOOO MUCH. I have a single course exam tomorrow, if i pass im gonna graduate. If i had money i would definitely buy a bottle of fine champagne but i dont :( I HOPE I PASS TOMORROW

[@hr-rf9yg]

amazing explanation! THANK YOU

[@vibhutikumar7415]

can you please explain why do we always assume that there is no interaction effect between blocks and treatments in a randomized block design?

[@aaronching6268]

Nice illustration mate!

[@anitabeilfuss4141]

Its pretty helpful, but when explaining about finding the averages between the 2 points and seeing if they are main effects, you never actually say if they are main effects or not. Or if the averages are indeed different, so that they are main effects.

[@leonierauch2477]

Actually at the end he's doing so - there are main effects for both variables :)

[@chrisotter3538]

Thank you so much, this really explained things clearly.

[@alexbb4093]

much respect, i am now more prepared for my final tomorrow

[@adrianageronimo1918]

what would you consider the independent and dependent variable on this experiment?

[@adrianageronimo1918]

would it be the percent correct?

[@JimGrange.]

@@adrianageronimo1918 The DV is percent correct. There are 2 IVs: (1) Sleep Deprivation; (2) Type of Supplement. IV is what you manipulate (or control). DV is what you measure.

[@adrianageronimo1918]

@@JimGrange. this was so helpful 😭 thank you!!!